Possibly. I've re-measured it though today in proper daylight and it's 120mm not 126mm - it looks like it's a Suntour Ultra 6 freewheel cassette.
At the worst I'll have a go at re-building it (never done that before), particularly if the spokes keep going.
OK that will be a big jump. I will try doing a search for wheelcraft and call them, also try Brick Lane Cycles as they may have something that works for you,even if its only a spare.

A short 6.1 miles for me, then!
. Two thirds of the way home, and the rear starts to feel spongy again. S put all my weight over the front wheel and pootled along at abput 5-6 mph to get to tone of the dry and lighted bus stops along the guided bus way.