Its always difficult to be precise, and as you say we tend to over react. Its a fact that when there is a problem anywhere in Europe many Americans cancel their holidays to everywhere in Europe.
Back to RP. I just saw that in 2007 it was anticipated that foreign tourism to RP would exceed 3million a year in 2008. If that is any where near correct then as percentage its practically an infinitesimal risk.
On the point of seeing police in RP.
The number of officers actually policing an area can seldom be estimated by the number of officers ones sees. I say that as a former police officer in London and 16 years as a volunteer interpreter with police in Spain. In that position I see the number of officers who patrol in civvies. There are considerably more of them than those in uniform, however, people still write to the papers complaining that there so few police on the streets.
I don't know the figures for police in RP so like everyone else I could only make a wild guess, which is usually totally wrong and seldom helpful.
