Worth a mention that the French acceptance in this thread is split into two:
One is a permit aircraft that fits well-defined historic criteria on design and end of production. (Actual dates, see LAA TL.2.08).
The other is to do with being ‘amateur built’ permit aircraft, and factory-built permit aircraft are not included.
LAA leaflet tl.2.08 is below. go to the sub heading ‘France’:
TL_2_08_Travelling_abroad_in_a_Permit_Aircraft_pdf
I"m sure the LAA has full-time staff. Maybe without the authority/knowledge to answer that.
The CAA received a paper question from me on 16/11/21 and it was immediately scanned and emailed to the appropriate person, who emailed the reply on 29/3/22.
There are two aspects here:
so both countries think it is ok to do that. Well, it’s been proven over many years that the Class 2 has near-zero predictive value, so this is good, but why only in an RV (etc) and not in say a PA28?
What is the rationale?
You can’t “ask the CAA” because there is nobody there with a brain answering emails or phone calls, and you can’t “ask the LAA” because there is nobody there (I am told they all have full time jobs) 
You need to ask UK CAA or LAA as France is just accepting what is accepted in the UK.
If you can’t fly a G reg.certified on a self declaration in the UK,.then you can’t in France.
A French pilot needs a Class2 medical to fly experimental in French airspace.
Can anyone explain the rationale of accepting a medical declaration if you are flying a “homebuilt” but not accepting it if you are flying a “certified”?
I struggle to explain this to someone else.
ULM in France is self declaration for everything. You just sign a piece of paper which says that on your honour the aircraft meets ULM regs that you are fit to fly and that you have the correct licence to fly it.
Some Brits at the weekend who arrived in a RV8 were asking about this and we were joking that sometimes you might be stopped by the air police and asked let’s say about being under MTOM especially after the Christmas eating binge. You just tell them that you are under MTOM " honestly sir" and they should take your word for it.
For Annexe 1 NPPL etc is it not explained in CAP733. I have seen a UK version somewhere.
You need permit to use NPPL(M) while flying G-reg Microlight in France, maybe worth checking with BMAA? the UK NPPL(A) is valid in France but need Class2 (although the exemption disappeared from the law but who cares), the Microlight need a permit to fly across borders
Also if you are planing to base it, I don’t get what are you trying to achieve?
Is it sub-525kg? YES
- You can convert NPPL to ULM with barely 2h flight with local ULM instructor, if you are current on type, especially if you arrive using it from UK before jumping in his ULM (they charge 60€ to sign the paper)
- Putting a Microlight on F-reg you get to enjoy more ULM freedom and better insurance terms
I don’t think that is generally true, and it may not be true at all.
This thread discusses whether the NPPL is valid in France.
The 28 days is a different thing. France and the UK concurrently brought in a rule – here that banned foreign reg uncertified aircraft being based there for more than 28 days. I don’t know whether this applies to ultralights but I am sure it does.
Regarding other countries, the UK LAA tries to block people keeping G-regs outside the UK – see e.g. here. Clearly you can get around it, either with a friendly LAA inspector who pretends he inspected your plane in the UK, or by flying it back to the UK once a year and pretending it lives there.
Are you allowed to keep a UK registered Microlight in the EU year around and fly with the NPPL as long as you don’t fly more than the allowed 28 consecutive in the case of France?
That’s what it says in Federation RSA literature also, pointing.out that it’s the LAA who are the “policemen” on UK reg. aircraft. But it also points out that it is a 2 way agreement and when French registered aircraft fly in UK it is the DGAC who are the " police"
What I mean by police is that if licence, medical is okay to fly a particular aircraft in the UK then the same applies when they are flying that in France for 28days and vice versa.
Meanwhile France are negotiating bilateral agreements with other European countries, along the same lines but some of them for the moment require a fee (possibly annual one) IIUC this seems to average around €90.
