In the UK we’re about to enter a further three weeks of lockdown. There’s growing pressure from Keir Starmer, the Labour Party’s new leader, for the Government to explain how we exit that lockdown. A lot of people are looking to technology to answer that, largely in the form of tracking applications. This article was going to be about how well that approach might work, until I remembered that it’s a good idea to understand the problem before trying to solve it. I’ll go into the details of contact tracking and tracing in my next article, but first we need to look at some history to see why we need it.