Removing the mesh?
 

Hi

My outside tortoise world has always had a 50cm square welded mesh underneath it to stop the fellas digging out as previously it has been on softish ground.

However now they are going on hard dry clay soil then I'm building up the soil inside with new soil for them to dig in.

So I was wondering if you think I could dispense with the mesh?

Don't underestimate their digging ability!
Saying that, my torts old enclosure had chicken wire under around 4" of soil and they never dug down that deep into it. Usually only 1-2" at best. They just go into their hides.
I've since moved them to a larger enclosure and haven't bothered with mesh this time. The soil is deeper and the sides are 4" wide railway sleepers so they would have to dig deep down and across a reasonable tunnel to get out. I check on them every day so I'm not too concerned at the moment.

I would keep the mesh. These animals are made to dig in hard dry soil.

Thanks I have kept it. Although having put them outside they are now back to their habit of hiding in the hides

Mine go in their hides and when in there they dig. If you get a lot of rain hard ground will soften a bit as well