A mix up that saw union members' private letters land on management desks at Wexham Park Hospital has further inflamed an ongoing dispute that has seen angry demonstrations at the main entrance.

The letters had been sent to Sir Andrew Morris - former chief executive at Wexham Park. In the letters union members asked him to use his new role as non-executive director of the NHS Improvement organisation which oversees hospital trusts, to intervene in the dispute.

But GMB regional organiser Gary Palmer says the letters to Sir Andrew were passed onto the new hospital bosses by NHI and landed on the desk of Wexham Park's deputy CEO Janet King.

The union is accusing all concerned of a possible breach of the Data Protection Act.

Mr Palmer said: "GMB are angry and disappointed that NHSI and/ or Sir Andrew are choosing to hand back private letters to the very employer they are critical of.

"GMB will now consider how we might best support and protect our members should the trust seek now to victimise or silence the very staff that have raised their concerns with NHSI regarding backdoor privatisation."

The current hospital management wants to set up a subsidiary company to take over non-clinical services - a move seen by some staff and their union the GMB as privatising their jobs.

The union believes the management plans would radically effect the security and rights of 1,000 porters, housekeeping, cleaning, security and catering staff.

But this week James Taylor - assistant head of communications for the trust - said the passing back to the hospital of the letters had all been a mistake.

He said: "A number of letters addressed to our former CEO Sir Andrew were forwarded to us from NHSI as it appears that they thought they were meant for our current chief executive.

"One letter was opened by a PA in our CEO’s office. When they realised the content of the letter, the others were left unopened on the assumption they were all similar. They remain sealed and we are in touch with NHSI so we can return them.

"We can assure staff that there has been no data breach."