Millions of taxpayers’ money was spent on maintaining Hammersmith Bridge while severe structural defects went undiagnosed.

The 132-year-old crossing was closed to vehicle traffic in April this year when engineers discovered microfractures in its cast iron base that may take three years to fix.

The shock decision sparked rows and generated headlines about how, over the last decade, and under both Conservative and Labour administrations, the bridge was allowed to fall into disrepair.

TfL spent £5.3 million on maintaining the bridge between 2015 and 2019, according to Hammersmith and Fulham Council leader Stephen Cowan, speaking a town hall meeting last month.

Now, using freedom of information requests, it can be revealed that this figure includes £1.65 million that TfL spent on minor repairs, and £2.61 million spent on “inspections, assessments, monitoring and surveying”.

Also since 2015, TfL spent nearly £900,000 on hiring wardens to ensure only two buses crossed the bridge at once. This was due to fears about how much weight it could withstand, but the council said in April that bus companies had “consistently breached” this rule.

During this time, a major repair job budgeted at £27 million was due to be carried out on the Grade II*-listed bridge in 2016. Those works ― which included replacing corroding bolts, resurfacing, and repainting ― were postponed to late 2017 but did not take place.

The bridge is owned by Hammersmith and Fulham Council. But like all major pieces of infrastructure in the capital, TfL contributes huge sums towards its upkeep.

A TfL spokesperson denied that the £5.3 million had not been a proper use of public money, and said decisions to carry out repairs are taken by the council.

At a town hall meeting in June, Mr Cowan defended his party’s tenure of the bridge.

Tory councillor Victoria Brocklebank-Fowler asked why the bridge had not been fixed sooner. “There was a negotiation with TfL but nothing happened, which led to this emergency closure… the knock-on effect has been horrific,” she said.

Mr Cowan replied there was no “breakdown in relationship” with TfL.  And he said the previous Conservative administration, which ran the council until 2014, had done nothing to assess or improve the bridge. 

He then said questions about the previously-scheduled repair jobs were a “separate issue”, because they would not have detected the fractures in the suspension bridge’s base.

Mr Cowan said: “In 2015 we commissioned a thorough review of its structural integrity… 

“What we found in April this year was a microfracture, which was completely surprising. That microfracture existed in a particular part of the bridge.

“The problem with a microfracture in cast iron is that it can shatter. So the idea that buses and cars are going across and this thing could shatter meant we had to immediately close the bridge.”

He added: “This is a new problem that only came about because in 2015 we began a series of thorough checks. That’s essentially the issue that led us to close the bridge. It is not a failure of our relationship with TfL… It’s a failure of a 132-year-old bridge which no-one checked for decades.”

The council has promised to return the bridge “to full working order” and reopen it to traffic. It said checks by engineers are due to be completed by September. This is when a timeframe for repairing the bridge and a cost estimate will be produced, the council has said.

It estimated in April that the works could cost £40 million. And a row ensued over whether the Government should pay for it.

Tory London Mayoral candidate Shaun Bailey last week told the Evening Standard that TfL should fund the repairs, using money it will no longer spend on the recently-abandoned Rotherhithe Bridge plans.

A spokesman for Mr Khan said he has asked TfL, which has a projected spending deficit this year of over £700 million, to work closely with the council on plans for repairing the bridge.