…..you can’t be fired for engaging in it.
Oh yes you can. Employers have always had the right to sack strikers. I don’t think there’s ever been a time in British history when they haven’t had that right. And it’s a right which they occasionally exercise.
EG Rupert Murdoch sacked 6,000 employees for going on strike.
Although obviously for practical reasons it easier for employers with smaller work forces to sack strikers.
And btw they must sack all those on strike, they can’t sack say just half of those on strike, that would be considered discrimination in the eyes of the law.