One of the roundabouts in Eastbourne host these rather strange huge plants. On looking them up I discover that they are called Century plants, even thought they live only 20-30 years and they flower just once in their lifetime - which these are now doing.
@ludwigsdiana. I think they just dry up, Diana, as some nearer the bottom have done already. I pass the roundabout often so will see in time, unless the local authority gardeners remove them as soon as they stop flowering and become untidy.