NHS London is re-examining a controversial analysis which concluded the capital’s hospital sector was “not sustainable in [its] present form”.

The Safe and Financially Effective analysis, carried out by the strategic health authority using McKinsey methodology, said London’s non-foundation trusts could | reduce their £1.5bn nursing spend by nearly a third.

Individual reports sent to trusts based on the analysis advised some they could reduce nursing spend by half if they matched the efficiency of peer trusts.

The report, drawn up in February, identified savings of £421m in the London nursing workforce. The figure formed the largest single part of the overall £1.2bn “theoretical productivity savings” it identified.

But a document released to HSJ under the Freedom of Information Act reveals NHS London has had to re-examine the numbers on nursing in the report.

The internal document setting out the work schedule for the SHA’s productivity support programme, a £4.6m scheme to improve efficiency at London non-foundation hospital trusts, said: “The SaFE analysis was perceived to be too high level to properly comprehend the nursing productivity challenge.”

It added: “Further analysis of the problem is required.”

NHS London confirmed a revision of initial figures had been carried out for the productivity support programme.

A spokesman said: “The first programme was a desktop review and the current pilot is a trust-based data collection exercise using a remodelled template.

“It takes account of a wider group of measures than the initial desk top review which was for indicative purposes only and clearly identified as such in the presentations to London trusts at the time. The recent pilot was developed by a group of senior nurses and nurse directors from the trusts in the pilot.”

One London source said: “This has all the hallmarks of an SHA winding down and rushing to use a budget, the last thing London trusts need at the moment is more hypothetical top-down analysis”.