It's pretty reasonable to assume that most TV's purchased as a replacement for an older model. Which makes Sony's latest offer of "up to" £150 of a new Bravia TV if you trade in an older set pretty darned good should you be in the market.
The full £150 is only available on Bravia's over 46in. For 40in TV's the discount is a lesser £100, and 26in to 37in models will only be reduced by £50. Nonetheless, if you were planning to throw your old TV away, it's still money for nothing, no matter how much of a rebate Sony is offering.
Perhaps detracting from the offer's appeal, slightly, Sony requires that the old TV be taking into a store - where you'll quite unsurprisingly have some paperwork to fill in - to get the discount, which is a bit of a pain. Sony promises that traded-in TVs will be recycled, so you could think of it as being paid to not chuck your old set in a landfill site if you like.
Interestingly while the size of discount given depends on the size of TV purchased, the size of TV traded in is irrelevant. Which reminds me, I'm pretty sure I have a 15in CRT sitting about somewhere...
The promotion will finish on 18 October, so if you've got a decent amount of time to get involved.