I have an 8 year old Meander PVC 'boil in the bag' size 4B. I'm 6' and about 13 stone - slim build, and it was a tad baggy twixt the thighs and around the belly, but it fulfilled a purpose.
However, the cuffs are knackered, but still velcro up, numerous small holes <1cm around the arse and elbows, bit worn in places around the crotch. Most of these have been glued/hot glued repeatedly, but still let in water/mud. Its been a faithfull servant on an exceedingly tough muddy dig and had just been replaced.
If you're planning 'orrible muddy, wet, squalid caving then get something else, but if you're doing nice, dry, warm, clean(!) caving, then it's got a fair life in it.
?15 postage free.