I have been playing around with a dummy Brecks data set and Mapmate - following Charles' Riccardia palmata post I pulled up a tetrad map of its distribution in Brecks. At moment the data only includes records at 1km or better, but at some point I will try and better localise some of the many 5km records and add those in as well. The map below therefore doesn't include a few 5km records that are illustrated in Ray's Flora - e.g. SO14SW, SN93NW . The species seems to be reasonably well distributed in the county.