Comment by Silhouette
16 years ago
I'm in the UK, and I have never had anything even close to this proposed to me, by any employer, of any size, regardless of how happily I left.
It's only boilerplate text if you're the kind of person who also accepted the "We own copyright to everything you ever do, at work or otherwise" clause in the employment contract.
I've been laid off twice, and both times the severance agreement included clauses that I basically agreed not to sue them for unfair dismissal. When I've quit, of course there was nothing like that.