Handbrake Return Spring Bedford Midi/Isuzu Fargo

[Pbill]

I own a 1988 Bedford Midi which is really and Isuzu Fargo. I noticed whilst under the car that the handbrake return spring is held on by a cable tie at one end of the spring. I need to replace the spring but I cannot locate one for my Van. For those of you with old or classic cars, where would you go to get a replacement spring?

I measured it today and point to point it is 25cm.

Any help would be appreciated as I am a bit stuck.