In reply to G1INK:
“in a straight line”. That is an interesting complication to the rule that I hadn’t realised before. It just so happens that I had been reading up on Gisborough Moor recently. This has the main top in square NZ6312 at a height of 329M, with a subsidiary top 1.9km to the NW at a height of 324M. There is a ridge connecting the two, curving slightly, with both summits and the ridge being wholly enclosed by the 310M contour. Hence I thought the NW top would be well within the activation zone.
However, if a straight line is plotted between the two tops, the lowest point on the straight line falls outside of the 300M contour; my version of Memory Map showing the lowest point as 298M. Therefore the NW top is outside of the activation zone.
Even more interestingly (if you are pedantic or like mathematical curiosities), you could pick a point say 200M west of the NW top (and about 14M below it), for which a straight line to the main SE top doesn’t fall below 304M, (actually about 309M).
Is that what was really intended? Without in any way wishing to start an argument (as I think the group who originally formulated the rules did a very good job), I would be interested in knowing why the word straight was put in the rule.