Assuming you were happy to leave it on the Thames...
Assuming that the system doesn't have to be mounted in a floaty, boaty thing, it seems to me that we have a pretty useful close air defence system there. Why not deploy it at all important military bases (i.e. targets)? Oh, I forgot, defence spending cuts. The money is to be spent on a rapid reaction force (read carrier groups) that can poke its nose into any other country's business anywhere in the world. Why would we ever need to defend the United Kingdom?