Update 20 April 2022 Daniel Clarke reviews the issue of proof of foreign law here.
Clarke v Kalecinski & Ors  EWHC 488 (QB) concerns a claim for damages for personal injury sustained during cosmetic surgery undergone by claimant on 7 January 2015. Claims is against the surgeon (domiciled and habitually resident in Poland; but also registered with the UK General Medical Council) who performed the breast and thigh procedures in Poland, and against the Clinic (a company incorporated in Poland in which the surgeon and his wife are the sole shareholders and directors), where the operations were carried out and she received pre-and post-operative treatment. Claimant also sues the insurer of the Clinic.
Jurisdiction is not disputed. Both surgeon and clinic are being sued under the consumer title of Brussels Ia. The insurance company is being sued under CJEU Odenbreit: subject to the applicable law of the tort and the existence under same of a direct right of action against an insurer, section 3 BIa gives claimant a right to sue in claimant’s domicile.
Claimant sues both surgeon and clinic, both in contract and in tort. She seeks to hold the clinic either directly or vicariously liable for the failures of the surgeons who treated her – one other Polish surgeon was involved in her care – and the nurses who cared for her at the clinic in Poland. Total potential liability for the insurance company, under the indemnity of the clinic (they do not insure the surgeon) is limited to approximately £38,500.
Proper law of the contract is English law, per A6(1) of the consumer title of Rome I. This is not disputed. It had been anticipated by claimant until trial that it was also a matter of agreement that the proper law of the claim in tort was Polish law, per Rome II. However in its skeleton argument, for the first time, the insurer raised an issue about the adequacy of claimant’s pleading arguing they had failed to plead the Polish law upon which they relied, so the proper law of the tortious claim was by default, English law. That was rejected by the judge on the basis of the exchange between parties.
At  ff Foster J discussed the application of A17 Rome II: the judge must take into account as a matter of fact, the rules of safety and conduct in force at the place and time of the event, i.e. Poland. However  the judge insists on the importance of the English standard of care
where it is a term of the contract that the first defendant would operate to the same standard as a UK surgeon, skilled in this specialism, and registered with the GMC, it is that standard, that applied to the activities in issue here. The care offered by the clinic likewise. [emphasis in the original]
Those terms of the contract were deduced by the judge :
[claimant] does not allege that she signed any contract or document, save for a consent form which the court has not seen. However, in my judgement the substance of the representations on the website upon which Ms Clarke clearly relied, were incorporated into the contract between her and the clinic together with Mr Kaleciński. In my judgement this was one contract but involving both parties: the surgeon and all the other care givers at the clinic, by means of the clinic (Noa Clinic Uslugi Sp. z o.o), those incorporated representations were to the following effect. The first defendant would carry out the surgery and he would carry it out to the standard to be expected of a GMC registered surgeon proficient in plastic surgery.
This emphasis by the judge imparts once again the relevance of language, no doubt for marketing purposes, for the consequential legal obligations. Foster J moreover holds 
That standard applies to the tortious duty also by reason of the representations made to which reference is made above.
and  she holds
the findings of [the expert] are couched in such stringent terms that they cover any surgical and indeed clinical practice whether governed by local Polish customs or not. The conclusions of [the expert] put paid to any subtlety of distinction between local custom and English practice that might … in other circumstances be considered relevant. What took place fell so far below acceptable standards I cannot accept the contention that local standards or practices might have rendered the egregious failings in this case acceptable as a matter of contractual or tortious obligation.
The judge’s findings on A17 Rome II are interesting. Yet I find her conclusions on website representations even more relevant.