North Wales was arguably the epicentre of British bryology in the 1970s and 1980s, and at the time of the first Atlas there was a general feeling that the mountains of Snowdonia (Eryri in Welsh) had been fully recorded. Mark Hill wrote A Bryophyte Flora of North Wales in 1988 and Marcus Yeo then spent many hours exploring the mountains in the early 1990s. People moved and attention shifted, and when A Bryophyte Red Data List for Wales was written in 2011 we found that many colonies of rare montane mosses had not actually been
reported for 25 to 30 years. Furthermore, most were only recorded in very broad-brush detail (in part because GPS had not been invented), often at the level of a cwm, and thus there was little chance of revisiting a population to check whether it was still extant or had declined or disappeared. The Countryside Council for Wales contracted Gordon Rothero to survey
three major cwms on the Yr Wyffda (Snowdon) massif in 2011, but solo recording in the vast landscape of Eryri is a challenge. The summer meeting of 2015 emerged from a suggestion by
Gordon that the best way to seek rare bryophytes in the mountains would be to send out teams of bryologists.