This may be the bottom of the current range but it is a superb phone. It does not have an answer machine as per the 6421 but I question if we really need those too much these days what with mobile phones etc.
18 hours talk time and only on 550 mAh could easily be improved with higher capacity batteries but it is not necessary.
This deal is £10 off but available online only. I emailed Sainsburys and they confirmed it was not available in store but they stated that they did not have an end date for the promotion.
The nearest price for this elsewhere is £29.99 so you save even after paying for the delivery (unless you spend over £100 and deliver midweek when it is free delivery).
The two phone model (6412) is poor value at £49.99 and the two handset answer phone model (6422) is available on Amazon for £44.99. that is good value against £29.99 but poor against this bargain at £19.99