Hungerhill Swallet, in the Peak District has a few choice squeezes.
The first one that did me was the squeeze from the mine level entrance to the top of Deep Space.
My first time through was in a 3mm wetsuit, I found the squeeze snug to say the least. On a second trip through I was wearing a 5mm wetsuit and when I got in the squeeze, I became tightly wedged with feet dangling some way above the floor.
Thinking I couldn't possibly have got that fat in a couple of weeks, I exhaled and forced my way through, feeling the ribs crack just I dropped through the narrow bit.
The only way to get back without a lot of pain, was to remove my wetsuit and inch back through, (this squeeze was enlarged sometime afterwards). Not by me I might add