Bill Birkett's book became a popular list for peak bagging in the Lake District, along with the equally popular Wainwrights. Because both lists are based on historical books, unlike for example the Murdos, their constituents remain fixed, regardless of revisions to height or other metrics. In this regard, they are similar to the Scottish lowlands, Donalds. The Long Distance Walkers Association maintains a register of people who have completed the Birketts. One of Birkett's peaks, Pillar Rock, which is also classed as a Nuttall, but not a Wainwright, requires climbing ropes and climbing equipment to summit.