The one I'm thinking of was on in the early 70s. It featured a man at the bar drinking a pint of Tetley bitter. He spots a good-looking lady heading towards him - bit of eye contact - but, as she gets near him, he just picks up his pint and carries on drinking. Tetley Bitter Men - if you can't beat 'em.
The last advertisement was done using the slogan Smoothly Does It, featuring a man in his twenties, usually coming up with an unusual yet successful solution to a common problem. Perhaps the most repeated advert featured the man in question on a crowded beach seeing a bar at the other end advertising Tetley's. The man then threw a stick towards the bar, attracting a wet dog to run across the beach to the bar, parting the crowd to allow him through.