Returning to the original query about the region allocation for Ailsa Craig GM/SS-246.
I have just consulted with my copy of “The Relative Hills of Britain” by Alan Dawson. This is the reference work for the Marilyns - the lists we use in the UK associations to define SOTA summits. (It is a fine reference work, well worth having a copy in the shack if you don’t already).
G, GW and GD are split into 14 regions (in the book), and we use these exact same regions in those associations. GM is split into 28 regions, and the following is taken from the ARM:
“The Marilyn programme splits Scotland into no less than 28 regions. Because of the extensive ranges of mountains throughout Scotland, it has been decided to split the country into simple geographically defined SOTA regions and map the Marilyn regions onto these”.
The GM SOTA regions include the following RHB regions:
Northern Scotland NS: 14, 15, 16
Central Scotland CS: 2, 5, 6, 9
Eastern Scotland ES: 7, 8, 21
Western Scotland WS: 3, 4, 10, 11, 12, 13, 18
Southern Scotland SS: 1, 19, 26, 27, 28
Scottish Islands SI: 17, 20, 22, 23, 24, 25
The interesting issue of the allocation of Ailsa Craig is now considered! In the RHB book, it is clearly in region 27 (which also includes a very large area of South West Scotland - mainland), and therefore in GM/SS for SOTA. However, the island is very close to the “border” with region 20, which includes the Isle of Arran. Looking at the map in the RHB book, it seems that the “border” could have just as easily have been drawn to include Ailsa Craig in region 20. Reading each sub-region description, it is hard to tell any particular reason why Ailsa Craig was put into region 27 rather than 20.
Region 27 it is though, and that means GM/SS for SOTA. As Ken pointed out, it is not the only example, there are others. All interesting stuff though!