I think you might be a bit late in the season but in years gone by I've had a decent haul from around the car park on Carlisle Lane over near Archbishops Park. Not sure if it's still a good spot - people keep building on wasteground. From my travels I think London's blackberries peaked a good few weeks ago though
Blackberries are ripening earlier and earlier. As a child we picked in September but this year I've been picking in August. On 22 and 31 August I went to Epping and easily picked 3 pounds on each occasion. If we have the rain which is forecast this weekend, there should be yet more. I pick adjacent to a rec ground - Cooperscale Common? Not that close to SE1 etc. (and I do have a Freedom Pass) but lovely food for free. (I freeze in 250 gr bags). Blackberry and apple crumble with ice cream or custard - yummy. I suspect you're correct that inner city blackberries are a dwindling thing but thought I'd post something a bit cheerful perhaps?
Blackberry & apple crumble isn't a pudding of choice on a sweltering hot day. This would mean imported cooking apples anyway ,summer's not for British ones. Aren't cultivated blackberries expensive ? They don't even taste half as good as scrumped ones .
SandyPandy. I wasn't suggesting cooking apple and blackberry crumble in the summer - as I said, I freeze the blackberries immediately after picking them. However, British cooking apples are available. I've never bought imported cookers. Just thought I'd clarify this!