Tesco have packs of 4 x 410g tins of Branston Baked Beans on a Buy One Get One Free offer.
The price per pack is currently showing as £1.57.
Tesco also have 800g jars of Hellmann's (real and light) mayonnaise at £3.19 and BOGOF. This offer wasn't displayed in my local store, but I presume the jars go through the tills at BOGOF.
This works out at the equivalent of 80p for a 400g jar and £1.20 for a 600g jar, so is pretty much unbeatable if you use a lot of this mayo.
BRANSTON SPAGHETTI 4 PACK ALSO BOGOF £1.97