Here's the account written by team member Robin Siddle:

British Museum; Commodus denarius donation to the national collection
 Visit October 2018
After finding my way to the upper floor of Greek and Roman life I was greeted by  Andrew Brown (National finds Advisor, Iron Age and Roman Coins) and  Richard Abdy (Curator of Roman and Iron Age coins.  
Upon entering a behind the scenes office area of the British museum I had a round the table meeting with Andrew, Richard and another member of their team. We began by having a discussion about Commodus and the coin that was being donated to the museum.  The paper work giving consent for the donation from myself and the landowners whose field the coin was found in was checked, copied and approved. Andrew explained that the museum were grateful for the donation particularly as this is a coin they don’t currently have in the national collection.  I explained that we were very happy to gift the coin to the museum and were excited about it being added to the collection. 
Richard nipped out of the meeting room for a minute and came back in with a tray of Commodus medallions, he then explained what they were used for and went into detail about the makeup of some of the medallions; one of particular interest was bimetallic, in a similar way to that of the modern two pound coins. I was passed on very large Roman military awarded medallion to hold which was brilliant, it was much heavier than I was expecting and not something I am likely to recover during a metal detecting survey.   
I was asked what period of coinage I was interested in and I explained my particular interest was in Roman coinage. I noted that we surveyed many sites of different periods producing various coinage and artefacts. I also mentioned that members of our survey team have an interest in the Saxon/early medieval period and that we are actively researching potential new sites.  Andrew noted that coin identification session are run at the BM looking at different period of Roman coinage and said that I would we welcome to attend.  
I explained that we had recently invited DigVentures to excavate a site where we had uncovered a small hoard of Vespasian denarii . Andrew was aware of DigVentures and the particular hoard I was referring to that was recorded through PAS. I mentioned that the site had gained  a lot of media coverage due to it being from an early period of occupation in the north of England. 

Using my IPad, I showed off the Priscan Image site using the Flickr platform and explained that after every survey, a detailed high resolution photographic report is produced of all notable finds. This information is then shared with the relevant landowners.  When scrolling down the photos, Andrew and Richard helped Identify a couple of recently found tricky to identify Roman coins, which will subsequently be recorded on PAS. Andrew also asked for a closer look at one find that we were unsure of, which was possible due to the close up shots that had been taken , he then  identified it as a fragment of  Belteus Decoration from a Roman military sword belt. This was very exciting to hear and something I am sure the landowner will be interested in.
Following the round the table discussion Andrew lead me down to the coin achieve.  It was pointed out to me where all the ancient Greek and Roman coins were housed. Andrew then located the section of Commodus coins and found the correct wooden tray where the newly donated denarius would be housed in perpetuity with similar reverse type coins.  The differences between some of the reverse types of the Commodus denarii was explained to me in detail.  Andrew then proceeded to pick out trays of Roman coins for me to examine and handle including coins from all periods. I was passed coins of all different types from gold Aureus to Sestertius which was fascinating. I was lucky enough to be trusted to handle a famous coin of Titus with a Colosseum type reverse which really made the day special as this is a coin I have read a lot about and not been fortunate to see first-hand let alone handle.

Richard was busy printing the new a coin label and added the donated denarius on to the BM’s database. I was then shown the new label, (with my name on it) and then it was placed on the coin tray along with the denarius ready for archiving.
My day at the museum then concluded with a walk around the public display areas of the museum.     

Today's survey was a visit to two fields that are side-by-side, one was 'worked' and the other ploughed.
The worked field has produced several denarii, a few fibulae and pottery including Samian Ware. An area where a denarii hoard was located was chosen to see if the working had disturbed any more denarii there.

A Roman trumpet fibula dating to the C2nd was recovered then the first denarius from the original hoard spot was detected. The emperor on the coin was Vespasian (69 - 79 AD) and had a copper green deposit adhered to its surface. The same deposit was also evident on a majority of the hoard coins too. 
A second denarius of Vespasian in the same area of the first coin was recovered and again, this had the copper deposit upon it.
Quite a few small sherds of Samian Ware were collected near to the denarii.
Nothing else was found in the large area searched surrounding the hoard site so we decided to move over to the ploughed field.

The second field was drilled with wheat and the shoots were about 3 inches long so the view of the surface was fairly good. This helped in the recovery of several sherds of Roman pottery with some very large pieces of rim sherd being found. Oyster shell and a Devils Toenail were also found on the field surface.
Part-way through the survey we saw footprints coming from the side of the field and back again. These were at 90 degree's to the field edge and looked as though whoever it was were using a wild bird crop cover to hide in if disturbed. Quite a few holes had been dug and some still had the greenwaste left in the holes.

Whoever the nighthawker was, he did a very amateurish job at searching the field as we found lots of Roman grots near to their footprints as well as a Roman brooch complete with its pin! He'd also missed a bronze numus of Allectus which was in fairly good condition. A siliqua of Valens and another denarius, this time it was that of Trajan,were also recovered in this area.
Our thoughts are that the nighthawker has been coming for years as they knew that this area was a particular "hot-spot". Imagine what must have stolen over the years!

Now for the technical bit.
Two machines were used, both running V5.2 and standard GMP mode with one machine fitted with the 9" HF coil and the other, the 13" X35 coil. 
Last week the 9" HF coil didn't find any of the 9 hammered Medieval coins compared to the 13" X35 machines which found all of them. The X35 machines also found the majority of the artefacts too.
This week it was the other way around where the 9" HF set-up found far more than the 13" X35..... again, this shows that you've got to walk over it and, as we use parallel lines, side-by-side, the soil conditions are the same so we can't use that excuse either. We also swapped lines regularly so the two of us were never on the same return leg of the field.
We are extremely comfortable with the end result of a survey as umpteen times now, one may find lots and the other two not as much or two will find lots and the third member nothing! Again, it proves that you have to walk over it!
A perfect example of this was that the X35 machine found the first 5 Roman bronze coins then, all of a sudden, the HF machine started to find coins and tripled the amount of Roman bronzes. The HF machine also recovered both Roman fibulae!

​HD images of the finds on the day can be seen here.

We visited a field we'd been to a year ago resulting in several recordable Roman artefacts and coins  being recovered.
The field had been drilled with Spring Barley and was just showing at about two inches in height.
Unfortunately, the field had only been cultivated and not ploughed and this was reflected in the lack of finds.
We tried the field adjacent to the first one and this was exactly the same.

Cutting our losses, we decided to visit another permission of which all the fields had been drilled, some cultivated and the others ploughed.
The cultivator on this particular farm has been designed to disturb the soil up to a minimum of 8 inches.
The field we chose was indeed cultivated but we knew that there are lots of cut Medieval coins and small artefacts there. Also, this field has been the target of nighthawkers due to the high level of coinage there. The bad news is that most of the full coins and larger artefacts have been stolen over the years therefore leaving behind the smaller, harder to find items such as the cut-quarters etc.

The site was strewn with hundreds of fragments of Medieval pottery dating between the C12th and C14th centuries.
Nine Medieval coins were recovered along with some lovely artefacts from the same era. One of the buckles was zoomorphic and one we'd not seen before. Of the nine Medieval coins, only two were "full" coins, these being a half-penny and a farthing. 
There is a very small Roman presence here too and this was in the form of a few Roman coins and 2 fibulae.

Two of the machines were fitted with the 9" HF coil using V5.2 with the third machine donning the 13" X35 coil and operating under V5.1.
The 13" X35 machine picked out all of the cut-quarters as well as three other hammered coins ending up with six Medieval coins! This is testament that the large coil will easily detect cut-quarters perhaps dispelling the myth that large coils "miss" small targets.

The remaining three hammered coins were picked out with the 9" HF coil.
Strangely, the third machine with the 9" HF coil (V5.2) didn't pick out any hammered coins! This is even though we surveyed in exactly the same way we do on every site, that is three-abreast, that part of the 18ft swathe didn't pass over any hammered coins at all.
When we reach the end of a pass, it is usually staggered, resulting in the return pass being in a totally different position! So, if I was on line 1 on the first pass, I might be on line two or three on the next one. This again shows that you've got to "walk over it" to find it.

High Definition images of all the finds on the day can be seen here.

And what a day it was too! Our first permission didn't turn out the way we expected with only a few Roman items being recovered. It was decided to abandon this site, which used to be one of our top venues, moving on to another permission.
The second permission is mainly Medieval and has only just been drilled after being worked, but not ploughed. Even so, we thought it may be worthwhile as we've recovered several cut hammered and other artefacts here in the past. Our thoughts are that there may have been some form of trading at the edge of the DMV. Finding lots of cut coinage in a particular area is a very good indicator that trading was going on there.

Sure enough, the first coinage started to appear as well as hundreds of fragments of Medieval pottery. Some lovely artefacts were also recovered.

​The full report will follow shortly, along with images from the day.