Icelandair I'm sure has featured in the report numerous times but never materialises.
I think we can also forget both Tunisair and Corendon who I believe have both gone to Gatwick.
The most interesting there is Norse, from my calculations that equates to about 7 slot pairs per day. I'd be very surprised if they can't get into Gatwick.
Another to watch out for is Fly Pop who appear to have two A330's panted in their livery, but are yet to go on sale or have any slots.