I began work on the concrete hardstanding area in front of the depot on Tuesday evening. I bought some Hobbycraft own brand clay as an experiment, this is what it looked like on Tuesday night:

And this is what it looked like on Wednesday morning:

Rubbish :-(

So, the way I've always done it is using Pollyfilla. You do get some cracking, but nothing like the picture above, and it seems to stick to the baseboard as well, unlike the clay which all came up really easily with light finger pressure. I ran out of Pollyfilla last night, here's what it currently looks like after I ripped all the clay up and put the new stuff down:

Hopefully when I get back from work it will still look like that, and I can get a new tub and finish the rest off.

Something else I bought at Hobbycraft was this 'medium buff' ballast, for an experiment, and I think it looks quite nice, certainly better than the rather boring grey stuff I used on the layout in the garage:

It now looks quite pleasingly realistic I think.