Sorry to keep going on about CAA/IAA and who does the oversight, but ......
If I recall correctly when a Far Eastern long haul airline was suspected of arriving at Heathrow with inadequate fuel reserves I believe it was the CAA who moved on that one, including requiring fuel quantity checks on each arriving flight, then after a while on a sample.
Now if the CAA could move on a safety issue then on a foreign airline operating into the UK, why cannot they make checks with the situation being discussed here.