May be limited to specific customers who have left Sky (like me) but I was only on a cheap package and only left 8 months ago so you may be able to get this deal as long as you used to have Sky.
I got a card through the door with the following offer:
1/2 price Sky for 12 months
£100 credited to account if you take Sky sports and/or movies.
So I rang them and after eventually getting the right department - "Winback" - I confirmed the deal and also that:
30 day rolling contract
No phone connection needed
£100 credited at start and only start taking money by DD once it runs out
So I went for the basic Variety mix plus Sky movies 2.
Costs £13.75 per month but only after the £100 runs out :-)
So free for approx. 7 months then I can cancel or keep the package for another 5 months at £13.75 per month after which it will revert to full price (or I can cancel then of course.)
I called 08442 410 651 and asked for the winback department then quoted "skytvb" as the offer code.
As I say, you may not get it if you did not get the mailer from Sky yourself, but you may have had it and binned it, or you may get the deal anyway if you ask :-)
ENDS 3rd July according to the mailer.