This essentially northerly species was regarded by Robson as '... decidedly rare here, Mr. Finlay being the only collector who took it at all regularly'. [...] The position in Durham has changed quite a lot since the turn of the century (prior to which there were only two records, from Darlington and Durham respectively). Beginning with a coastal record for Blackhall Rocks in 1929 (J. Baxter) it has been steadily extending its range westwards. Thus it was found at Barnard Castle by J. P. Robson in 1932 and at Chester-le-Street by TCD in 1955 and at Waldridge Fell about the same time. There was then a rush of records for mid-Durham in the 1960's and 1970's, reaching as far west as Middleton-in-Teesdale (I. Findlay) in 1974, Hamsterley Forest in 1981 (TCD), Langdon Beck in Upper Teesdale in 1980 (I. Findlay) and Crooks Altar near Westgate, Weardale in the same year (R. Woods), often involving up to a dozen specimens each year. It is therefore presently regarded as widespread, and becoming more common each year.