January 2021 Update
The maps are below, incorporating data from 2000 to present.
The method was kindly provided by Brian Pitkin of Surrey Botanical Society. The Surrey analysis is available in the Records section of the society’s website, www.surreyflora.org.uk. Any errors in the data or presentation are of course my own.
The method relies on a list of 1km squares originally sourced from the Biological Records Centre VC Grid Squares request page. This data was also provided by Brian Pitkin as a map-like spreadsheet, showing the percentage of each square contained within VC 5 and VC 6. Note that the extent of each vice-county extends to low water mark, which accounts for the large coastal expanse of red (zero-count) squares, particularly around the mouth of the Parrett. In addition, the Herbaria United OS Grid Reference to Vice-County converter was found to be very useful in checking grid references against the VC boundaries.
The original method relied on the use of Access97 (the underlying database software used by MapMate). As this is no longer widely available, and the Access97 files are not accessible from newer versions of Access, the decision was taken to export all the record, site and taxon data from MapMate and then process it in Access 2016. This involved creating MapMate User Queries to display the records, sites and taxa and then saving them as text files. These were used as source data to create tables in Access2016.
From that point, the SQL queries provided by Brian Pitkin were used successfully to generate the required data. The counts were copied into the spreadsheet, also provided by Brian.
The record and taxon counts were exported from Access and copied into an Excel spreadsheet. Conditional Formatting has been used to colour each square according to its value. Again, this was designed by Brian Pitkin although we have added an additional colour to represent squares with more than 300 records or taxa.