David Chaum is American, which wouldn't explain Satoshi's use of British spellings. For example, glancing over his last posts in the forums I've found one (https://bitcointalk.org/index.php?topic=1790.msg28715#msg28715) where he writes "modernised" and another one (https://bitcointalk.org/index.php?topic=1850.msg22952#msg22952) where he uses "formalised". It'd be very unusual for an American to use these "-ise" spellings that appear in Satoshi's writings. Add to that the fact that he inserted a quote about British bank bailouts from The Times in the genesis block, and it looks like Satoshi is probably British or must have had a closer connection with the UK than with America.