It really is a non event because you have to clear customs on first landing in the european empire and again before leaving. If customs are on demand you have to demand for UK passport holders anyway.
There is nothing specific according to the colour of the passport. If you land and no customs officer is present you have still cleared customs - I rarely find a customs officer
And before anyone suggests I am not following the rules, I have been 'ramp checked' by French customs officers at private sites on two occasions. The first time they flew 120 miles from Paris in a AS355 because another helicopter in the party had not passed through a customs airport. The helicopter is question was G registered and owned and flown by a UK passport holder....They were threatening to impose eye watering fines but agreed not to if yours truly was checked. I had a non UK passport holder and told them there was no customs officer at Calais. All happy. I presume for these French chappies flying around in AS355s at £1200 an hour just to check a passport it is vital to ensure no non Schenegen people arrive without following the rules, but they consider a British passport the same as any other one with a visa.