Where to buy basic A/V stuff (cables, etc) in London?

I should really have asked this earlier - where is a decent place to go in London (that is readily accessible by foot-falcon and/or public transport from Shoreditch) to get basic gear like a 10m S-Video cable, RCA cables, etc? I seem to recall walking in to a Maplins (?) or something like that a few months ago - though don't know if there is one around here.

Also, never having used a BNC cable before, interested in being able to connect to one - I have VGA and S-Video out from my laptop, and an S-Video to composite adapter (assuming I haven't lost it... but I don't know where it is right now!), though I can't plug that directly into my lappy without some sort of gender-bender or in-betwixt cable.

-spxl

maplins
london wall
( just by liverpool st station)

www.cpc.co.uk - loads better than maplins but without the walk-in shops.
also www.vdctrading.com if you want proper video leads ;)

Thankyou! :o)