My opinion (worth sod all) is this:
Parallel runway airports ALWAYS say Left or Right on every transmission every time.
UK ATC bollock you then you either deserved it - or - he's having a bad day and CRM strongly suggests you take it because next week you'll be having a bad day and make the same mistake AND you'll regret it on the drive home.
Final point, ATCOs and Pilots always enjoy each others company at the bar - fourth law of flying.
Cheers
WWW