For many British people, apologising is a default reaction to
life's little irritants. This highly illogical response is deeply
ingrained in the British psyche. If someone barges into you, treads
on your toe, or spills your drink, it is quite normal to mutter
Obviously this is not a normal apology - a heartfelt mea culpa for a blunder. In fact, the British apology is a strange, strangled version of the outraged "do you mind?" of more confrontational cultures.
British people are well aware of this enigmatic agenda. When they commit an offence (a minor infringement of pavement etiquette for example) and are met with the requisite "sorry", they are quite likely to respond in kind. This can lead to a surreal escalation of apologies, which have very little to do with real feelings of regret.
Visitors to Britain should be aware that the word "sorry" is devalued currency. Trivial transgressions (fumbling for change, dropping a pen) will inevitably involve apologies, and most transactions will involve the word "sorry" at some point.
Just go with the flow. Don't take the apologies seriously; be aware that sometimes the word "sorry" is not an admission of guilt but an (albeit muted) accusation. The British "sorry" is highly infectious and you'll soon find yourself reciprocating. If you find yourself muttering "sorry" when a boorish drunkard knocks over your glass, you'll realise you have truly assimilated.