I'm thinking it might be the entrance to the Memorial Garden in Penlee Park. I don't think so but this is really irking me because I know I have seen it. In spite of racking my brains, it won't come to me!
So very, very close so I will accept your answer, tpp. Yes, it's in Penlee Park but near Penlee House and your answer was a mere 5-10 yards away, if that. It's part of the 1982 - 1992 Anniversary stone and I'll post the full picture. Well done tpp! ::7: