Transport for London is in a fix. On the one hand it is the most lavishly funded transport organisation in the country. On the other, it is stretched to breaking point operating probably the most extensive and sophisticated network of trains and buses in Europe.

Crossrail, the £15bn-plus joint venture with the Department for Transport to build a new rail line across the capital, is making matters worse.

Headlines highlighting a series of delays that have pushed the opening date from last December to as far away as 2021 are causing huge damage to TfL’s reputation. The cost overruns that add about £1.4bn to the original £15.4bn price tag contribute to its woes.

A good part of London’s success in attracting business from around the world is its transport system. The trains are fast and the bus system is rapidly making the switch away from diesel. The point is that, within huge constraints, progress happens and usually for the better.

TfL ranks as among the toughest and best-run public sector organisations. Pitch its procurement managers against those running the Ministry of Defence buying team and it’s not so much Tottenham versus Manchester City as Barcelona taking on Notts County.

Critics are right to point out that TfL has paid staff handsomely to get things done. It has plenty of six-figure-salaried suits dotted about its offices in St James’s and tube drivers have used their muscle to extract wage rises over many years while pay across the UK has flatlined.

Yet none of these attacks compares with the destructive impact from its handling of Crossrail. The correspondence published by TfL between its executives and the mayor’s office shows a degree of wishful thinking that can only be described as disturbing.

If TfL cannot keep a project within reasonable cost and time limits, what hope do the executives running HS2 have, MPs will rightly ask.

But even a glance at the details of Crossrail illustrates the difficulties TfL faced completing Europe’s largest infrastructure project and how a focus on the negative would mean nothing got built. Always remember, Berlin’s international airport is scheduled to open in October 2020, almost a decade later than originally planned and at four times the original €2bn cost.