Following useful advice from RMWebbers and a blinding flash which told me what I should have been seeing all along. Any comments will be VERY welcome.
I've numbered levers from the up direction - is this right?
1 - Home
2 - Loop point and trap from loop
3 - FPL
4 - Dummy for loop
5 - Dummy for goods shed
6 - Goods yard and trap
7 - FPL
8 - Release crossover
9 - Dummy for engine release
10 - Starter
11 - Dummy from loop to main
12 - Dummy from goods yard
13 - Loco Shed