When the Liberals returned to power in December 1905, Macnamara's political prospects were thought to be rosy. After two or three years, W. T. Stead forecast, the older veterans would retire, and having served his apprenticeship, he would attain Cabinet rank:

But when Asquith succeeded Campbell-Bannerman in April 1908, Macnamara, because of his refusal of the post offered to him at the Board of Education, was only fourteen months into his ministerial career. The Government benches were crowded with ambitious young men. Macnamara always retained an affection for the old Prime Minister: ‘one of the most large-hearted, kindly, simple and honest men I have ever met’, he recalled fourteen years later. Campbell-Bannerman, a wealthy Scot unconcerned with rank or with the ties of university and school so dear to so many early twentieth-century Englishmen, had admired and encouraged him. Asquith, in contrast, was drawn, especially through the ambition and influence of his second wife, into aristocratic circles. ‘He enjoys the grand life’, Sir George Riddell, the solicitor, director of the News of the World and Lloyd George's constant adviser between 1913 and 1922, wrote in his diary in May 1912: ‘He likes to live amongst wealthy and fashionable people.’