There is good and bad.
On occasions, travelling out of London City, I have connected with an Edelweiss flight in Switzerland. The tray meals they serve have always been appetising - and far superior to those served by their parent company, Swiss.
The worst meal was on a charter out of Gatwick with a company I fortunately cannot remember. The odour of reheated roast lamb, dowsed in vinegary mint sauce was enough to push the whole tray away!