Another big infrastructure project, another set of delays. Nobody could have been that shocked by Crossrail’s admission last month that it would not be opening by Christmas and could be up to a year late. And where there are delays there are inevitably cost overruns – about £600m in this case, which the government fessed up to earlier in the summer.

The British public is used to this sort of bad news. Comparisons with the Channel Tunnel are hard to avoid – remember the embarrassment around that highly sensitive project going a year late and an eye-watering 80% over budget?

The odd thing is that until relatively recently Crossrail was being lauded as the UK’s flagship project where all was tickety-boo, everything running on time and on budget. The National Audit Office was satisfied progress was on track back in 2014. Nothing to see here, we were told. So what changed?

The immediate cause of the delay has been testing problems with the signalling software. Linking new underground systems with overground sections is not straightforward and was made more difficult by an explosion at an electricity substation last year. Unfortunate, but not really a construction issue.

It didn’t escape journalists’ notice that the news was slipped out on the last Friday in August in a press release that omitted to mention the word ‘delay’  – referring instead to a ‘revised schedule’

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