Hi Ross, In answer to your question about black and white vintage postcards featuring Briercliffe, as far as I know there is nowhere in Burnley where you can purchase such cards, mores the pity.
The only way that I know of is to try and bid on e bay for them, as some do come up from time to time.
I myself have to make do with vintage photos of Briercliffe in any books that I am likely to purchase.
I will stand and be corrected on this information though.
Wish I could have been of more help.
Stephanie.