Thames/Heathrow - G-LIZZ: It weren't me, honest!
Just as an added thought for the GA guys:
When we have staffing issues, the initial course of action might be to regulate the known IFR traffic to prevent overload. This will probably involve applying flow control to issue slot times, MDIs/ADIs, NBTs etc. and can cause lengthy delays.
So when you pitch up at the zone boundary requesting a transit, and you're told to remain outside for 10 minutes, just think that the IFR traffic ahead of you could have been sat on the ground for an hour or two, full of passengers, taking their delay without complaint. I know it's easy to look at the snapshot of traffic you hear on the r/t, but take a moment to think about the big picture.
You can prevent all this frustration with a quick call to us before you depart. Let us know what you plan to do and we'll advise whether we can accomodate and any delays you might get. I guarantee we will always do our best to fit you in, and if we can't there will always be a good reason.