Boxtops....where in Lewes (The Grange ? im Lewes born and bred ) Foxglove trees are similar....but have a different growth habbit and the obvious lilac blue flowers in may.
Im head gardener for preston Rock Garden Opposite preston park in Brighton.....if you're ever there, pop over and i'll show you round.
Thanks hammerman, I'm not often over in Brighton these days but thank you! I think it's in the Gun Gardens according to the interweb (I know it was in the area of the Grange gardens when I visited with my mother, it's a huge tall tree). It was many years ago though, it may not still be there.