The development of hill lists in the UK has been very fragmented over the years. All lists have a summit height criterion and most have a prominence criterion too.
Before surveying the varying height and prominence criteria, we should deal with the 'elephant in the room'. The majority of traditional lists have had a fundamental problem since the early 1970s because their criteria do not match the Ordnance Survey maps used by most walkers. This means that it is hard to relate hill lists to maps and not straightforward to check the criteria on which the lists are based. In fact, these list criteria are fundamentally based on maps made obsolete more than 30 years ago.
Reproduced from Ordnance Survey map data by permission of Ordnance Survey, © Crown copyright.
The commonly used 1:50 000 Landranger maps have principal (thick) contours at 50 metre intervals and finer ones at 10 metre intervals. Spot heights of course are also measured in metres.
Consider height criteria from common hill lists with the following common upper or lower criteria for height
All of these criteria are off contour, especially major (50 metre interval) ones, and therefore not map-friendly.
Corbetts and Donalds were introduced well before the Ordnance Survey's move to metric mapping in the 1970s. Consequently, they do have prominence criteria in feet. The popular hill lists that have come along since have either declared prominence criteria from the outset at 15, 30 or 150 metres or refined them to these figures since. Of course, these figures have been chosen because of their proximity to 50, 100 and 500 feet.
Back in 1891, the quality of mapping information available to Sir Hugh Munro was deficient and he wisely chose not to attempt a strict prominence criterion. All 3000 foot Scottish summits with a prominence over 144 metres are Munros and all those with a prominence below 55 metres are not afforded Munro status and included only as 'Tops'. This leaves 154 summits with prominences between 55 and 144 metres, of which 75 are Munros and 79 are not. The Prominent Peaks database includes 259 of the 284 Munros, together with 14 Munro Tops.
Seen as a whole, the traditional lists have a fragmented way of combining height and prominence as well as being geographically fragmented.
Of the historic lists, the Corbetts, Grahams and Marilyns have the largest qualifying prominence criterion. In particular, the Corbetts have been praised for being generally interesting peaks. It is no accident that they have a demanding prominence criterion.
There is a need for a unified approach to height and prominence criteria that fits with modern metric maps.