I've never seen salmon side at less than £10 per kg so this is a bargain. Weirdly, it wasn't even an offer, just priced up like that on the shelf!
In date until 21st Dec. I would suggest portioning it and then freezing it. Perfect for Christmas! They don't have the 1kg on the Asda website but I would assume it's national. I found this in Asda Crawley.