Better is the enemy of good. It’s a saying that is drummed into every rookie courtroom advocate, and is reminder that an insistence on perfection can lead to disaster. The example that’s sometimes used is of a defence barrister who famously sought to argue that his client had not bitten off the ear of a victim. He initially cross-examined the star witness successfully. Having noted the poor lighting and considerable distance he asked “You didn’t actually see him bite the victim’s ear, did you?” “No” came the response. Unable to resist a ‘perfect’ demolition he asked the fatal further question: “In fact, you didn’t see him anywhere near his ear, did you?” “True,” said the witness, “but I saw him spit it out”.

I was reminded of this when I saw the report in the Echo recently about an all-singing, all-dancing £500m tunnel proposal for the A417 Air Balloon scheme. This scheme looked fantastic on the CGIs of course. And what’s not to like about a tunnel? But, I am concerned that we should not fall into the trap that experience has identified.

£500m is a huge amount of money. To put it in context, the Transport Department’s so-called ‘departmental expenditure limit’ for capital funding in 2017-2018 is £7.6bn. In other words, £500m is not far off 7% of the entire current annual capital budget.

This must not be allowed to become the price tag which sinks the project if more cost-effective schemes are available. That’s because getting a solution is absolutely vital. The road, used by 34,000 vehicles a day, has seen more than 340 casualties in the last 15 years, several of them fatal. Air quality is poor and regular logjams are preventing businesses in Cheltenham from competing with neighbouring regions.

Getting the Government to commit to spending £250m on this was tough enough, on the basis of the cheaper ‘Loop’ scheme. Getting them to double that, at a time when we want to restore doctor-led night-time A&E and get more funding to the schools front-line would be tougher still. Nor do we want one infrastructure project to ‘crowd out’ everything else. I would like to see Junction 10 of the M5 made four-way for example.

We’re now in the consultation phase, and it’s important that all schemes are given due consideration. But in deciding on the final one, let’s not forget the wisdom of our forbears: better is indeed the enemy of good.