Well I gone and suffered a bad case of chainsuck. Blasting through town on my way to last weeks "Radnor Fringe" festival I went for a quick up shift on the front mech. I thought the chain engaged and then as I was about to apply power there was a clang and the crank stopped dead. A quick downwards glance confirmed the worst: the chain was hitched up the backside of the chainwheel and had jammed in the cage of the front mech.
After coasting to a halt to sort it out, it transpired that the derailleur, an almost new IRD double, was also bent.