Ofcom was asked in a Freedom of Information request to provide a list of Available/Reserved amateur radio callsigns for the UK and Crown Dependencies

The database can be useful for people wanting to apply for a specific call sign as it shows calls which are not available for issue.

Those who've passed the RSGB Full exam have the option of applying for callsigns from the old G and M call blocks including G3, G4, G5 and M5.

Ofcom released a spreadsheet containing 146,469 callsigns with a status of either Allocated or Reserved.

Status categorisation:

‘Allocated’ means that the callsign is currently assigned to a station under an Amateur Radio licence. It is therefore not currently available for assignment to anyone else.
‘Reserved’ means that the callsign has been used within the past two years, although it is no longer, and is in the process of ‘cooling down’. It is therefore not currently available for assignment to anyone else, but operators will be able to apply for it again after the two-year period has expired.