Is 32 enough?

I am building a new rear wheel and can get hold of a cheap 32 spoke on-one rear hub. It will be laced to a deep v rim. What I want to know is whether this will be strong enough to deal with my 15 stone mass?

yes

I concur.

Deep v is a good choice if stiffness is what your after.

Yep, it'll be fine. You have either a deep section rim and 32 spokes, or 36 spokes and small section rim. The deep rim spreads out the load across more spokes, hence the need for less spokes to distribute the weight in the same way as a small section rim with 36 spokes. if you go for 36+deep you're just riding with extra weight and slightly more air resistance.

What about a 24 spoke front wheel? On Deep V rims?

Hmmm, difficult to say. What's it going to be used for? I wouldn't want to ride on anything less than 32 spokes on London streets or anywhere where there are particularly large number of pot holes. In a velodrome I think it'd be ok. When the wheel is built you want the spoke tension to be as high as possible without deforming the rim, so if you can get the tension high enough with 24 spokes it'd be ok I suppose. I don't think the benefits are worth it though, to be honest.

I am a large marge. 32s hold me fine and i built them myself.
currently running on-one double fix rear and campag front.

Cyclocross wheels are less spoke count and they seem fine too, though i may change them to counter the post xmas bulge.

You'll be fine!

32 is more than enough. Everyone should be killed off at 30; like in Logan's Run.

I ran a Mavic Open Sport cheapo shallow rim on 32 with no problems, and I'm 17 stone

People are actually admitting to being heavier than me? hahahahaa

OP: 32H is fine. I wouldn't go below that in the 'old days' but I've got over it now and my Ribble road bike has been fine with 24radial front/28 rear and it has ridden over everything and done quite a few kilometres.
They were in fact bought used, off a larger guy than me and I've never trued them.