A Norfolk MP yesterday expressed surprise at a decision by the Serious Fraud Office to drop an investigation into the management of Keydata, which left thousands of investors out of pocket.

Investigators at the Serious Fraud Office (SFO) said they had found insufficient evidence for a criminal prosecution into the running of the firm. The probe was launched after the firm was closed down in 2009 by the Financial Services Authority (FSA).

Many of those who had invested in Keydata did so on the advice of staff working for the Norwich and Peterborough Building Society.

But the criminal investigation was entirely separate to the compensation ruling the by Financial Services Compensation Scheme, which said that investors would be able to get some of their money back.

North Norfolk MP Norman Lamb said he was surprised and disappointed at the SFO decision because it contradicted the views of the FSA that there was a criminal case to answer.

'I'm surprised because the FSA gave a very clear impression that there was prima facie evidence that criminal offences had been committed,' he said.

The N&P was one of the biggest sellers of Keydata policies, selling them to more than 3,000 of its own customers.

The society was recently fined �1.4m by the FSA for mis-selling the Keydata polices and is compensating them to the tune of �51m.

It is now in the process of being taken over by the Yorkshire building society after the compensation bill plunged it into the red for the last financial year.