Correct me if i'm wrong but to keep an FAA instrument rating current is it still-6 approaches and 6 hours instrument flying in 6 months(done mine in 1993 and let it lapse,so I dont know if the rules have changed)And from what I remember some of it can be done on a sim.
At least if this is still the case the pilot is more current than following the UK IMC currency requirements.
Remember that a UK CPL automatically has an IMC rating that does not need revalidating,so a pilot could go for longer than 25 months without flying in IMC then 1 day get caught out and still be legal.