This cordless electric kettle is stainless steel (so your tea doesn't taste of plastic), it has a water gauge which lights up (so you don't boil more than you need), it uses 3KW power (boils fast), and has a limescale filter and pop up lid. It comes with a 2 year guarantee but you can register it on the Russell Hobbs website to get a 3rd year. All in all this was the best value kettle I could find. True, it does not have 'half price' or a higher price crossed out shown, but that doesn't mean this isn't good value at £19.99.
Here it is on the Russell Hobbs website: http://uk.russellhobbs.com/russell-hobbs-products/kettles/coloured-kettles/illuminating-pennine-kettle-20444.html
There is a caveat to the guarantee in the instructions, as it advises it should be descaled monthly and states products returned because of faults due to scale will be subject to a repair charge.
Free click-and-collect to store. 1% Topcashback and probably similar at other cash back sites. 5% cash back for holders of the PS Black Card and possibly similar cards.