I noticed a big banner at Bosworth Water Park ( Leicestershire ) advertising a "Classic Car Meet" on (I think) the last tuesday of every month.

A bit of Googling and I found a Facebook Gallery, Facebook Gallery... but not much else.

Looks like an eclectic selection !

There is a car show listed for the 29th September, here is the link but not much information and nothing about times and entry fees.
http://www.bosworthwatertrust.co.uk/events

I get the impression that it is pretty informal.
On all day, until the park closes at dusk.
Pay the normal £2 car park fee.

I went once a couple of year ago. Mainly yanks a few classics, but there no reason not to change that! Would be tricky if it doubled in size though