My favourite is the Warburton bread advert,with the bread lorries rolling off into the dawn with all the staff coming out to wave goodbye, as if they are going into battle. Stiff upper lips, chaps - be brave!!
Cravendale milk mentioned above. Also (I'm surprised no one has mentioned this yet) the BirRABEye polar bear adverts from May & June this year (for peas, fish fingers & chicken dippers respectively). A new one for salmon fillets has just come out but it's not as good.