If they are "E" marked they are fine.
As far as I am aware harnesses with an aircraft style buckle release are not "E" marked, and those with a regular style belt release are.
Out in the big wide world you would probably get away with them at MOT time but at a pedantic garage it would be a fail.
2008: VW1 3rd in Class
2009: VW1 3rd in Class
2011: Ginetta Challenge
2012 Ginetta GT5 Challenge/Golf GTI Championship 2014 BRSCC Production GTI Championship
Think its road legal as long as the buckle release mechanism on the harness is not a quick release or twist lock :!:
AFAIK as long as the harness has a push button release its legal
Most harnesses ( or they used to) state whether they are road legal or not :?: :!: