The map and list depict the P600m Peaks - a list of British and Irish hills with at least 600m of prominence, also known as the Major Mountains of Britain & Ireland.  One of the hills, Rois-Bheinn, could be substituted by Beinn Odhar Bheag - both have a height of 882m, so you could assign to either the 774m prominence, and both should be climbed.

For more information, visit Mark Trengove's Europeaklist website and download the PDF/leaflet from the bottom of the United Kingdom page.