That looks like a Maxview aerial. Back in 1976 in the Cambridge area, our local aerial contractors fitted them as standard. Maxview is a Kings Lynn company - still going - that nowadays makes a feature of aerials for caravans, boats etc.
http://www.maxview.co.uk/support-and-information
Ours seemed to work pretty well in those primitive days when the only stereo FM available in Cambridge was all the way from Wrotham. Fortunately, signal distribution has improved since then!
I always wondered whether there was any theoretical basis for that 'delta' dipole element. I decided it was probably just a more robust folded dipole designed to withstand the fenland winds!
Martin