I am not relying on the 70% figure, Steve. Back in March, according the oracle that is "The Daily Mail" Sir Patrick Vallance said around 60 per cent of the population will need to catch the virus to build up a national tolerance strong enough to stop the virus circulating. I am sure I could find similar reporting from other papers. but that is the one that came up first. It may be 60%. It may be 70%, it may be 93%, or 43%: we really have very little way of knowing yet. Until we have at least one substantial community with widespread infection or vaccination you are essentially trying to estimate where a curve 'flattens off' while you are still on a piece with a high gradient.

But I was really trying to make a different point. It was if you need to have a certain level to achieve herd immunity, what do you do when, for whatever reason, you cannot get to that percentage? That will require a judgement call at some time.