Speaking at the Commercial Bar Association in London, Sir Thomas said Britain could no longer consider itself as the international standard bearer of liberty and justice.
'In the European Convention an instrument lies ready to hand which, if not providing an ideal solution, none the less offers a clear improvement on the present position,' he said.
Sir Thomas said that the increase in size and power of the executive had been striking, as had been the weakening of parliamentary influence.
'Where does this leave the protection of human rights? Not in a very satisfactory position, I would suggest. The elective dictatorship of the majority means that, by and large, the government of the day can get its way, even when its majority is small.'
Neither Parliament nor the judiciary could prevent a government of 'sinister intent' from disregarding human rights, he said.
And the need for safeguards had increased as a result of post-war immigration and changes to Britain's culture.
'Some of these more recent citizens have shown less willingness to be submerged in the prevailing British way of life . . . than most of their predecessors.' At the same time, there was less deference towards authority.
'So it seems reasonable to predict a growing number of cases . . . in which the prevailing practice will be said to infringe the human rights of some smaller group or some individual. As it stands, our courts are not well-fitted to mediate in these situations.'
Sir Thomas also attempted to counter some of the arguments used against incorporation of the convention into English law. Critics of the convention say that politicians, rather than judges, should determine the issues at the heart of the debate on human rights.
But Sir Thomas said: 'No one familiar with the development of the law . . . could, I think, fairly accuse judges of throwing their weight on the side of the big battalions against the small man or woman.'
Neither was it sensible to 'entrust the decision of these questions to an international panel of judges in Strasbourg - some of them drawn from societies markedly unlike our own - but not in the first instance, to our judges here.'
Incorporation of the convention into English law would 'stifle the insidious and damaging belief that it is necessary to go abroad to obtain justice'.