CAT21 is currently arranged to place on 21st August at the Midland Air Museum in Coventry – http://www.midlandairmuseum.co.uk/
see https://forum.batc.org.uk/viewtopic.php?f=135&t=7503 for more details.
Details of previous CATs, including presentations and videos of the event can be found on the BATC wiki pages:
CAT20 – Online: https://wiki.batc.org.uk/CAT_20
CAT19 Didcot: https://wiki.batc.org.uk/CAT_19_South
CAT19 Finningley: https://wiki.batc.org.uk/CAT_19_Finningley
CAT18 and the BATC General Meeting was held at the Midland Air Museum on the weekend of September 15th and 16th 2018 – https://wiki.batc.org.uk/CAT_18
CAT17 was held at Finningley Radio club – https://wiki.batc.tv/CAT_17
Videos from previous CATs can be found on the BATC Youtube channel – https://www.youtube.com/channel/UCUWLnUZllytlcCFd93tnBzw
BATC also attends various radio rallies around the country with the BATC shop and Portsdown Clinic.
Full details of these events are posted on the BATC forum
A full list of rallies in the UK can be found on the RSGB website.