anti-tank weapons, possibly NLAWs? Those trainers were actually from the Ranger Regiment, who are just grunts - "craphats".

SAS' specialty is sabotage and the Paras are elite shock troops, operating behind enemy lines. If someone was training the Ukrainians in the tactics of holding defensive positions, it would be the Rangers, but the British would be behind the curve, compared to Ukrainians, in dealing with drones and thermobarics

I know of ex-Paras who went to Ukraine as mercenaries. What exactly serving Paras are doing in testing a purposefully nebulous "new defensive capability" is difficult to parse. They're more likely to be going on the offensive.

Chris Ryan (Bravo Two Zero) had been reserve SAS. To join the SAS proper, he first had to go through Para selection, which he partially failed (passed level two, failed level three). He subsequently passed the SAS selection.

Para training is particularly painful. From one data point, the dropout rate in Para selection was something like 45 out of 50, dropping to just 1 left after three years.

Both those elite units play the part of the enemy in army exercises. When craphats are captured or surrender, they do not get treated gently!