Tractorboy, thanks for the tips. It's a while since I checked the TMZ (not been down that way for quite a while) but was under the impression that if you did not have Mode S you have to talk to Stansted/Essex when in the TMZ below 1,500 ft (this assumes you have Mode C)?/
You are quite right - sorry. All our aircraft have Mode S so I never bother.
In that case, just talk to them. They're not ogres, and there have been times that I actually asked for a radio check as I hadn't heard anything on frequency for 10-15 mins after tuning in. Then there other times when they're really busy.
I have only ever been refused a transit once, and it was VERY busy that day - and quite often have to hold just shy of the airfield boundary. Getting to scoot through the ILS between 2 incoming Ryanairs, their TCAS systems blaring, is great fun.