eBay and Craigslist finds

Quite easy to check if the seller co-operates.
Put a good fork in the headtube and measure the distance BB- front HB c-t-c.
Compare this with the Kirk geometry that you've looked up on the internet : http://www.kirk-bicycles.co.uk/Kirk-Facts.htm
A bit of work, but it gives you some kind of security (at least if the frame is bent or not). Of course, the fork rake has to be the same as Kirk's original.

I had one of these a couple of years ago and from the pics I would say the forks are very bent.
Also I snapped the chain side chainstay whils stomping up Hedsor Hill near Maidenhead.

The trashed frame ended up in the middle of the village bonfire on the next Guy Fawkes night.
It was awsome when it ignited: Beams of white light radiating from the middle of the fire. The vicar thought ET had arrived.

...d.e p..