We have to be very careful. The worrying matter of money laundering in scale has been raised by a recent Channel 4 investigation and program in July as well as the Private Eye mapping of British property interests of companies based in tax havens. If money laundering has been happening on a significant scale - and there seems to be quite strong suggestions that it has - then the properties acquired as a result may not appear on the market for a considerable time again, if ever (without extreme government and/or legal intervention). The potential future property supply has therefore been reduced.
Lowering stamp tax now without concrete investigation into the extent of money laundering and better enforcement of anti-money laundering may just encourage more criminal activities and therefore lead to a further reduction in long-term supply.
The message - yes transaction taxes are too high - but corruption and criminal activity also seem way too high too (sadly we will never be completely free of both). All need to be tackled quickly, not just transaction taxes.