At first, I thought I'd done quite a good job on the hut roof. A base coat of Humbrol leather streaked with rust while still wet. In my mind, once liberally dusted with weathering powders and perhaps a little plastic solvent for extra texture (it attacks the paint, making it wrinkle) the results would be lovely.
However, while painting, I wondered what the panel at the front of the hut was supposed to be. After pondering for a while, I realised it should be asbestos.
So, back to the paint pot for a basic asbestos mix. More 121 with loads of talcum powder flicked on to it from a wide brush. Then, when a bit dry, even more talk worked in from the brush directly. If the paint peels off in places, recoat and add more talc.
Asbestos does need the texture. At the moment it's too clean but the final weathering will sort this out.