First time for me posting on here as I usually just sit back and read away!
I bought an old type Karrimor Alplite pack from the gear sale at The Heights in Llanberis last year. It had a dedicated pocket for a pack frame but no frame but at the bargain price of £5 that I paid for the pack I decided to purchase the pack and then attempt to source a frame elsewhere.
Days of searching then concluded in finding a company named Lancashire Sports Repairs (www.lancashiresportsrepairs.co.uk) who repair rucksacks and plenty of other outdoor gear (boot repairs, sleeping bag repairs, clothing repairs, tent repairs, gaiter repairs, rock shoe and approach shoe repairs and re-proofing etc...) for the likes of Karrimor, Lowe Alpine, Vaude, Macpac and Berghaus (among others). It resulted in me emailing them a description with measurements/dimensions of the frame I needed and they made me one to order for about £25 I think it was.
It fits like a glove and I've had no issues with it so far so I highly recommend these guys so they're definately worth contacting.