The original design was by a C (G?) R H Simpson and described by Gearge Gentry in ME 1935 and 6.
I presume the Dick Stockings design is the latest but Horley would be able to tell you that.
Seems to be plenty of staying on this one but it appears to differ from the boiler drawings I have for the Stockings design.:- Just looked a bit closer at the drawing and I see it is the same. The staying is at 1" pitch with additional support round the fire hole.

Edited By Old Elan on 12/10/2016 13:24:08
Edited By Old Elan on 12/10/2016 13:34:16