Thanks for the replies so far.
We all know the customer is always right and if the guy wants a leather apron surely, it is his problem wether its too hot.
I am in the UK, so not exactly a hot country and wear leather work aprons for sewing, woodwork and metal bashing.
I have so far tested upholstery leather and waxed veg tan.
The first was surprisingly good.
The second a disaster.
My initial thoughts were deer or goat.
Any further thoughts please ?