I think you may have cracked it, Guy.padfield wrote:... any of the letters in the word 'butterfly'?
'Map' shares the same property, but that doesn't really qualify as British.
This question reminded me of the old trivia chestnut about the unique property of 'St Johns Wood' tube station. It was certainly true in the 1980s, but some of the more recently-built stations may have invalidated it.
Paul