Peter wrote:
Does it have an ICAO CofA?
Hi Peter, I think it does. The previous owner registered as an “Ryan STA Special”, so it’s not an experimental.
Are you “permanently relocating” to the UK?
Where will the airplane ultimately live?
I used to live in London but moved permanently to Amsterdam in 2018. So now I split my time between the two cities. In the end it turns out there is more hangarage to choose from around London than there is around Amsterdam. That was the deciding factor. Weather is equally bad in both places. :)
If that is the case, you would leave it on N-register and fly, case closed
For a certified aircraft there is no issue operating in the UK. Brussels has mandated EASA pilot papers, so you need the FAA ones plus the European ones.
That would be great news if this is the case! I’ll read up on the EASA regs.
This is the actual plane, after about a one year restoration process, flying over Southern California. It carries the Dutch air-force markings as Silvaire mentioned:
Ok I found my record in the FAA registry:
https://registry.faa.gov/AircraftInquiry/NNum_Results.aspx?NNumbertxt=7779
So definitely not an experimental…
Contact the LAA first. Then the CAA. The LAA might be able to give you useful contacts if it’s not something they could handle.
They do some warbird trainers
PS It looks like one of the very, very few aircraft suitable for modern flight training, equipped for social distancing of trainee and instructor.
The plane is registered as an ST-A, meaning that like most ST-As it is in FAA standard category – ST-As were a certified aircraft sold to the general public.
There is no issue with operating a standard category aircraft anywhere in the world on N-register, and assuming it adequately conforms to TCDS for an ST-A there will be no problem with the Annual Inspection sign-off by a European based FAA A&P IA. Do pay attention to the latter point as European based IAs with no antique aircraft background may not be particularly tolerant of inconsequential but unapproved mods and may be drawn to differences between STM and ST-A configuration. If nothing else, pick your IA carefully.
Well that’s excellent news.
anywhere in the world on N-register
Except Norway, Denmark, and most of the 3rd World 
Here are all the Ryan Aeronautical type certificate data sheets – I couldn’t post a link that would repeat the search on the FAA website. Given that the plane is visually an STM which seemingly has no civilian TC, when annual inspection time comes along its important to know which standard category TC covers the plane.
Per the FAA Registry Link, the aircraft appears to be a Ryan ST-A, TC 571. Here is the associated TCDS Note that the eligible engine listed is a Menasco Pirate C4, which is a 125 HP non-supercharged engine, which is different than the engine used on the non-certified military STM.
A post above says the plane is an ST-A Special, which is TC 681. This one had the same supercharged C4-S as the STM. Here is the associated TCDS listing the supercharged engine. Other details did vary between ST-A Special and STM, cockpit opening shape etc. Happily none of that stuff is listed on the rudimentary TCDS of the time but a key issue may be what data is listed on the airframe data plate. On antiques these are not standardized which may be useful here, and it may be very useful to ensure the data plate as well as the configuration of the plane does not directly contradict ATC 681 and the associated TCDS. It would also be very useful to get the CD (or whatever electronic form is current) with the FAA aircraft records all the way back to day one.
This stuff could become relevant when you switch to a new A&P IA in a country where there may be fewer IAs to choose from. The problem should not be with importation or operation of a standard category FAA certified aircraft in the UK. However once you’re away from ‘home’ (for the plane) it could possibly be an issue getting an FAA certified antique with no type support organization and a possibly unclear FAA certification basis through Annual Inspection. You will need to find the ‘right A&P IA’
Tread carefully 
Hope it works out well.
A good friend of mine Peter Holloway owned and operated a Ryan STA out of Old Warden for about 3 years till 2017 when it was sold to a new owner in Norway.I accompanied the aircraft in my Robin DR400 as as an escort ,baggage ferry and transport home for the pilot on its delivery flight initially to Denmark.It was always on the N register having lived for many years in Germany and was purchased from there after it’s owner died.A fabulous looking aircraft I understand challenging to fly. It was always parked with a champagne bucket as it’s drip tray.I never flew it though I did a lot of time time on Peters PT 22.The STA was maintained at Old Warden by the Shuttleworth collection and the chief engineer John (Jean) Munn would be a very good guy to talk to.John was the pilot for the delivery ferry flight to Denmark…a very talented man.PM me if you need phone numbers for him or PH.
Regards Stampe
