"Tourists" - EXACTLY. UK earns
$50B/a from tourists and we should not discourage them (I just avoid London). I am concerned for the innocent would-be visitor who simply does not realise a 5 minute bus journey can cost £3 (when used to 30ȼ) and so spends time/money/effort arriving in UK only to be turned back and for the one who thinks £1k might not be considered enough by UK, I'll go to France instead.