I'm in one-hundred percent agreement, Atch!
The examples you gave such as Lawson are only apt because they are such assimilated Jews with impeccably British-sounding names, that they don't stand out as ethnically "different", as would for example if his name were "Samuel Jacobovits" or something similar:-)
Benjamin Disraeli retained his surname, but DID convert to Christianity. Why? For acceptance among his gentile peers, of course.
Therefore, people indeed don't care whether somebody's Jewish or not...as long as they aren't publically or annoyingly identifiable as such.
Read in a major British newspaper a while back that in fact a certain posh Devon resort was being "taken over" (their words, not mine) by the Ultra-Orthodox, often dressed in full regalia, schreimels and all:-)
Let's just say, the latter were not named Nigel Lawson or even John BerkowLOL