What the?! This is contradicting everything I've heard so far
I don't think it is:
All Licensing Action remains under the jurisdiction of individual member staes of EASA.
In IN-2014/114 the UK CAA clearly states that any EASA Examiner can conduct a Skill Test, LPC, etc on a UK Licence Holder.
However they also clearly state that a non-UK Examiner
is not entitled to take any administrative action on behalf of the CAA.
Revalidating by experience only involves administrative action, so a non-UK Examiner may not sign your Licence.
Given that it is only the UK CAA (as far as I know) that extends administrative privileges to its Examiners this is not unreasonanble.
Is my revalidation valid or not?
I would suggest not.
You would need to either find a UK Examiner to sign your paperwork or send it all off to Gatwick for the CAA to undertake the administrative action required.