The collapse of engineering giant Carillion will cost taxpayers an estimated £148 million, according to a new National Audit Office investigation.

The public spending watchdog has examined the government’s response to the firm’s financial troubles and eventual liquidation.

But what does today’s report tell us about the impact on the education sector?

Here are five things the NAO report reveals about Carillion’s business in schools.

1. The Department for Education estimated that its contingency plans for the collapse of Carillion would cost £3 million

The NAO report gives a breakdown of the contingency plan costs from government departments and public bodies which had contracts with the doomed engineering firm.

The DfE’s estimated cost of a contingency plan for Carillion’s liquidations was £3 million. It is not yet known what the actual cost to the department or the schools sector will be.

2. Carillion had contracts to build schools when it collapsed

The National Audit Office report reveals that Carillion had two contracts with the DfE under the Priority Schools Building Programme, and six in total.

The report does not identify what has happened to this work. It has previously been revealed that Carillion was the contractor for a PSBP scheme to build eight schools in the Midlands.

3. School contracts were profitable for Carillion

The report shows that Carillion received £79 million from the education sector in 2016-17. This was a small part of the total £1.7 billion revenue it received from across the public sector.

However, the report notes that the company’s profit margins from work in schools were between 13 and 15 per cent, in contrast to central government facilities management work, which had profit margins between 4.5 per cent and 5.5 per cent.

4. Carillion had more than 300 contracts with schools

Schools accounted for almost three-quarters of Carillion’s contracts with public bodies. The company worked with schools in 26 local authority areas across the country. This included providing facilities services for Oxfordshire County Council schools.

The NAO says Carillion had contracts with 97 schools in Oxfordshire, 62 in Tameside, 63 in Stockport and with other schools across 23 areas. In total, it had 312 contracts with schools and 423 public sector contracts in total.

5. The Cabinet Office was concerned about the impact of Carillion’s collapse on schools

The NAO report shows how the Cabinet Office stepped in to ensure that public services continued. It provided £150 million to allow the company to continue to trade while being wound up.

This is the first time this had ever happened, according to the Insolvency Service. The report says that the Cabinet Office was broadly satisfied with central government’s readiness for Carillion’s collapse but it had wanted to see improvements in the planning in schools.