Mr Taber said: "Such a close split decision raises massive issues over the role of the regulators in this. In particular, the full judgment makes no reference to the arguments made in court over the statutory requirements that [bond] prospectuses should be accurate and contain all the information investors need to make an informed decision.

"If the courts will not consider these statutory requirements in interpreting prospectuses then it must fall on the Financial Conduct Authority [the City regulator].

"Despite my repeated requests to Andrew Bailey [the head of the FCA] to make the information available to the Supreme Court, the regulators have refused to disclose exactly what they and Lloyds knew about forthcoming changes to capital requirements at the time the ECNS were issued.

"I believe the changes they knew about, which were not disclosed in the ECN prospectus, meant that a capital disqualification event was a certainty at the time the ECNs were issued. If the court had been told this I think it would have made a difference."

Alexis Brassey of Cavendish Legal Group, who was involved in the bondholders' fight, said: "The 3:2 result shows the issues in this case were far from clear.

"It is surprising that the Supreme Court allowed Lloyds to deprive investors of their return on what can only be described as a convoluted technicality based on a conceded drafting error in the document [which Lloyds had admitted at the High Court].