Plusnet just called to remind me that my contract is up, they've offered Fibre Extra (which is what I am currently on) for £27 a month including line rental matching what Sky can offer. The benefit for me apart from the static IP, is that I get to watch BT Sport on Sky for £12.49 a month (although that will be half price for the first 6 months) whereas it's far more expensive to add it onto Sky going to BT directly. The downside is that I can't stream it online or watch it on the app but I can live without that. I think the closest I can get is the BT Unlimited 2 offer with BT Sports but that would work out more expensive as it comes into £54.99 a month and PlusNet will be £39.49. I guess I get the £110 gift card but I really don't want to go with BT as my ISP.
This will be my 3rd or 4th year with PlusNet and I've been very happy with them. I know I could probably save a few £ here and there if I looked around but I don't think I can get a better deal taking BT Sport on Sky into account. FWIW I tend to watch every PL and Championship game that's televised so it's not something I would be prepared to be without.
Edit, PlusNet have sent me the confirmation and it's 12 months only, I've asked them to confirm this as 18 months was mentioned on the call.
I can get a £110 gift card with BT, plus £105 cashback with TCC although it's an 18 month contract. That said I'm not really comfortable switching to them.