the handing over a pre-typed letter
What tosh - it implies that the letter was all done in the 'typing pool' (do companies still have those?) beforehand with a presumption of guilt. A company like BA will have had HR prepare the letters and had them vetted by Legal in advance when faced with a situation like this, i.e. strike added to history of behaviour of some during past strikes. There will also have been a 'you're cleared' letter. It's just a case of slotting in Dear [Your Name Here].