They are mostly found in seaside towns outside piers and shops. Although I have yet to search for their urban counterparts, I suspect inland ice cream signs are mostly in the form of the evil cornetto (a parody of an ice cream that lacks the irony of a Mr Whippy and with packaging that misses the point of the cone).
I must admit, I'm not that keen on Mr Whippys, having been spoilt by the yummy Hockings.
But I'm a fan of the signs. I like the simplicity of their design as well as the naive silliness of using giant versions of food as advertising. I guess they resonate with my nostalgic love of anything from my childhood that looks as if it has a diminishing future. These signs I'm sure will gradually be replaced by over-coloured cornettos (you may have guesed I really don't like these!).
But most of all I think it's the incongruity with their surroundings, run down seaside towns, rainy holidays and cold grey days on the coast. And whatever the weather, a seaside ice cream is always something special. Especially a giant plastic one.