Ok, I now know the part number I am looking for, I need the JST B2B-XH-A and the pins are SXH-001T-P0.6.

I found the detail, including a full spec sheet here:

http://www.rcgroups.com/forums/showpost.php?p=6061305&postcount=6

RS UK don't seem to have them, some of the more further flung RS websites have it, but have it discontinued. Lots of far east component websites claim to have it, but I suspect they will want me to buy lots of them

Edit:

Found them here, just trying to place an order now:

http://www.pldaniels.com/rcshop/frame.php?vp=CONN-JST-XH3