Wouldn't it be argued that you were undertaking a car that was indicating? Was there a bike lane?
I remember reading something about UK traffic law stating that you aren't meant to 'filter' along kerb.
Edit: I checked and only found something that recommends against it (not stating it is illegal):
http://www.survivalskills.clara.net/riding_skills_20.htm
It's a webpage for motorcyclists, but interesting nevertheless.
@Polkatronixx started
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I remember reading something about UK traffic law stating that you aren't meant to 'filter' along kerb.
Edit: I checked and only found something that recommends against it (not stating it is illegal):
http://www.survivalskills.clara.net/riding_skills_20.htm
It's a webpage for motorcyclists, but interesting nevertheless.