It is interesting to imagine the legal position in Lambert v Motor Insurers’ Bureau (Rev1)  EWHC 583 (QB) in a scenario of retained EU law post Brexit, rather than firmly within the scope of the Brussels Ia Regulation and applicable law under Rome II. By the mechanisms of EU consumer law and EU insurance law, mixed with the finest legal machinery in the area of subrogation, a UK resident party injured in a motor accident (here: at a private racing circuit in Spain) abroad is entitled to claim compensation from the Motor Insurers’ Bureau (‘MIB’) in certain circumstances, clarified by the UKSC in Moreno v MIB  UKSC 52. Crowther DJ summarises these circumstances as 
broadly speaking, that the guarantee fund of the member State in which the accident occurred would be liable to compensate the injured person on the facts of the individual case, when applying the rules of the local law which govern such actions by injured persons against the local guarantee fund. In other words, if Mr Lambert can show that the Spanish guarantee fund would have been liable to him in respect of the accident, he can claim such compensation from the MIB as would have been payable by the local guarantee fund. It is common ground in this case that the scope of the insurance obligation for use of motor vehicles under Spanish law extended to cover participation in the track event, notwithstanding the fact that it was not on a road or other public place.
The latter element is unlike the UK where seemingly third party motor insurance for motor sport is not commercially available.
The law applicable to the claim is agreed to be English law. While not specified in the judgment, this is presumably because of Article 4(2) Rome II (where the person claimed to be liable and the person sustaining damage both have their habitual residence in the same country at the time when the damage occurs, the law of that country shall apply): both Mr Lambert, claimant, and Mr Prentice, said to be responsible for the accident, were participants in a track event, organised by a UK based track day operating outfit called Track Sense; both travelled to Spain from the UK.
Spanish law however determines the preliminary issue as highlighted by the Supreme Court, Spanish law being the law which would have been applicable to any hypothetical claim which Mr Lambert might have brought against the Spanish guarantee fund. This is where things get interesting. The Motor Insurance Directives support a direct claim against one’s national MIB, subject to the law of the MS where the accident happened, sustaining liability in the circumstances. However Rome II somewhat curtails its action radius by declaring that it does not apply to ‘evidence and procedure’. This is a carve-out which is problematic in specific instances as I explain ia here. On such instance are issues of limitation however these it seems ([14)] were not pursued.
In the case at issue, parties’ agreement () is that by analogy to A1(3) Rome II, matters of evidence and procedure are outside the scope of the material substantive law and fall to be determined in accordance with English law as the law of the forum (lex fori in principle determines issues of evidence and procedure). Equally, on an analogous basis to A22(1) Rome II, parties agree that Spanish law will apply insofar as it contains rules which raise presumptions of law or determine the burden of proof.
The common law treating foreign law as fact, means the content of that foreign law is established often with the help of parties (if need be cross-examined) experts however  is for the English judge to determine. The remainder of the case therefore is spent discussing the expert evidence (with the judge doing some fine distinguishing of the case-law both experts referred to) together with the factual elements, to conclude 
Mr Lambert’s actions were 25% causative of the accident and Mr Prentice’s 75%. It follows that Mr Lambert’s claim for damages against MIB succeeds to the extent of 75% of his loss or damage.
Lest my understanding of the insurance Directives fails me (which it could well do), this means that claim on 75% of the damage remains to be judged under English tort law. With presumably a repeat of the causation test, this time under English law.
A clearly written judgment which no doubt benefitted from the considerable practice experience of the judge on the matters at hand.