Don't think for one second I'm right, it could be a scout from the planet zog!
Lancing used to be invaded by stag beetles within the last thirty years....but I've not seen any for a good length of time.
If it's over a couple of inches long, I'd say stag, if under, chafer. If only HWT had...
Cockchafer grub. May bug, June bug. Very similar to Stag beetle but they're rarer than rocking horse droppings where as the chafer beetle is everywhere.
Chafers about 1" to 1 1/2" Stag beetle up to 4"