Some were discussing this on HMVF forum
http://hmvf.co.uk/forumvb/archive/in...p/t-15610.html
These claim to sell Pig brake partshttp://www.powertrackbrakes.co.uk/parts.html
There's a Pig for sale on MilWeb that lists brake repairs by MVRT (whoever they are) perhaps they can give a lead? MVRT's web page is
http://www.mvrt.co.uk/page_1232746215250.html
Found on Olive-drab.com "Western Resources. British wheeled armour. Ferrets, Saracen, Stalwart, Humber Pig. M35 trucks. Vehicles, military paint, 24v light bulbs, and parts. (Joseph Francis). PO Box 907, Rogersville, TN 37857. 423-272-0690, 423-272-9450 fax."
Another option would be to take the old hose to a hydraulic hose fabricator and ask if they can make you up a new one. I have been told that this can be a surprisingly reasonably priced option. In Ottawa I would start at Diotte Hydraulics or similar
www.diotteshydraulics.on.ca/suppliers.htm might give ideas about others who might help in your area since Diotte seems to be local to Ottawa.
I don't know how many of these paths you've already looked at... Good luck finding what you need.