If I understand correctly the trend is going toward banning all "pointy" knives of some size, primarily large kitchen knives with a sharp tip. The rationale being that such knives have no practical value in the kitchen as confirmed by "10 top chefs from around the UK".
That's already old news, the same idea has been around for a while:
http://news.bbc.co.uk/2/hi/health/4581871.stmSo if one takes the idea further, a large kitchen knife with a blunt tip (e.g. sheepsfoot) would be considered ok. The same type of knife with a sharp tip would be classified as an "offensive weapon".
However, the recent Lancashire amnesty referred to in the original post clearly extends to all sorts of knives, including machetes. Which IMO implies that all knives and long bladed cutting tools are essentially considered dangerous weapons.
I suppose pretty soon some genius will discover that you don't even need a knife in the kitchen - think Microwave Dinner!