Starbucks - Buy One Drink, Get One Free with prtinable voucher at Starbucks @ London Evening Standard
Apologies if this has already been posted? - I couldnt see it.
Buy one get one free on Starbucks drinks until 10th August with voucher.
The voucher is from the London Standard newspaper and does say 'take a moment to stop and enjoy London' but in the small print and actual voucher it just states 'nearest store'.
Tried the voucher in Northampton (not London) and it worked for me, hopefully it will work for you too!