Paul. You might like to try P&O. Yes they are American owned but still run in a fairly british way. There is a gratuity at the end of the cruise but all seems well managed and civilised. certainly the service is excellent and mostly the ships are small enough not to be anonymous. Above all, they arent full of yanks who always seem the most charming people in their own country but thoroughly offputting abroad en masse.
Mind you I am sure the same could be said about some parts of british society as on the costas.