The former chiefs of two banks are to appeal directly to HBOS shareholders this week in a bid to oust the group's top brass and scupper the Lloyds TSB takeover.
Its follows Saturday's announcement that board members "unanimously" rejected Sir George Mathewson and Sir Peter Burt proposals, which would force out HBOS's chairman and chief executive.
The former RBS and Bank of Scotland bosses want to replace the ousted men and scrap the merger plans in favour of a recapitalised stand-alone bank. They will now lobby shareholders directly over the issue.
The attempted boardroom putsch came to light in a letter by Sir George and Sir Peter addressed to HBOS chairman Lord Stevenson.
In it, the respected bankers stated that the £12bn merger was "no longer necessary" given the Treasury's plans to inject cash into UK's creaking banking sector.
Instead, Sir George and Sir Peter proposed taking over at the top of HBOS and re-evaluating the situation.
The letter accuses Lord Stevenson of being "determined" to continue with the takeover despite "terms which are perversely made worse for HBOS shareholders" by the Treasury's rescue package for banks.
The missive makes clear that Sir George and Sir Peter prefer independence for HBOS rather than a search for other suitors.
"We firmly believe that a standalone recapitalised HBOS, which has a strategic plan agreed and new management teams put into place will represent far greater upside and stability than the Lloyds takeover," the letter reads.
But it adds: "If, however, Lloyds makes a more appropriate commercial offer for HBOS that too will be given full consideration."
