Peer Pressure
1922-1922: A. Bonar Law (Conservative)
1922-1927: Arthur Lee, Baron Lee of Fareham (Conservative)[1]
1922: J. R. Clynes (Labour), H. H. Asquith (Liberal), David Lloyd George (National Liberal)
1927-1927: Arthur Lee, Baron Lee of Fareham (Conservative minority)
1927-1928: J. Ramsay MacDonald (Labour minority with Liberal Confidence and Supply)
1927: Arthur Lee, Baron Lee of Fareham (Conservative), David Lloyd George (Liberal)
1928-1931: Sir W. Laming Worthington-Evans (Conservative)
1928: J. Ramsay MacDonald (Labour), David Lloyd George (Liberal)
1931-1933: William Peel, 2nd Viscount Peel (Conservative)
1933-1935: Arthur Henderson (Labour)[2]
1933: William Peel, 2nd Viscount Peel (Conservative), David Lloyd George (Liberal)
1935: (acting) Sir Charles Philip Trevelyan (Labour)
1935-1938: Josiah Wedgwood (Labour)
1935-1938: Josiah Wedgwood (Labour minority with Liberal Confidence and Supply)
1938-1938: Hon. Walter Guinness (Conservative minority)
1938 (Feb): Josiah Wedgwood (Labour) Hon. Arthur Murray (Liberal)
1938-1938: Josiah Wedgwood (Labour)
1938 (Jun): Hon. Walter Guinness (Conservative) Hon. Arthur Murray (Liberal)
1938-1939: Wilfrid Ashley (‘Peace’ National Coalition)[3]
1938 (Nov): Josiah Wedgwood (Labour), Sydney Arnold, Baron Arnold ('Peace' Labour), Walter Guinness ('War' Conservatives) Hon. Arthur Murray (Liberal)
1938-1939: Roundell Palmer, Viscount Wolmer (‘Peacetime’ National Coalition)
1939-1939: Roundell Palmer, Viscount Wolmer (Conservative minority)[4]
1939-1939: George Isaacs (Labour)[5]
1939: Roundell Palmer, Viscount Wolmer (Conservative), Sir William Edge (Liberal), Frederick Pethick-Lawrence ('Peace' Labour)
1939-: Dudley Leigh Aman, 1st Baron Morley (Labour in Wartime Coalition with Conservatives and Liberals)[6]
[1] After Bonar Law rather unexpectedly lost his seat in the 1922 General Election (on account of a rather massive swing to Labour) - the Conservatives were in a bit of a pinch - they had still won a majority after all. The two main contenders seemed to be Lord Curzon - who was however widely disliked, and Stanley Baldwin, who had only been Chancellor of the Exchequer for less than a month. MP for 18 years, military man, and former Minister of Agriculture and Fisheries, and First Lord of the Admiralty, the hardworking Lee was a perfect choice for a third option to break the deadlock - and as a fed up Bonar Law declined to get back into government, what had initially been a caretaker government dragged on and on. Lord Lee ended up holding on - through strikes and discontent - to 1927, when the Labour Party finally broke into government. Lee watched from afar as MacDonald's government began to collapse - and ultimately gave up the leadership to his handpicked successor, Foreign Secretary Worthington-Evans.
[2] Henderson had taken over from MacDonald in 1931, at the height of the economic downturn which neither Worthington Evans or Lord Peel (the only Prime Minister to be the grandson of a former Prime Minister until Lord Wolmer) seemed to have a clue how to handle. 1933 was of course a massive election victory for Labour (and the main thing people think of when they think of Henderson nowadays) and he managed to hold his fractious party together and get quite a large chunk of his political agenda passed, before resigning in 1935 due to ill-health.
[3] Josiah Wedgwood's aggressive attitude towards the Czechoslovakian crisis prompted a sizable rebellion in the Labour Party - which combined with widespread Conservative desire to reach some sort of deal led to a pleased King Edward VII inviting Wilfrid Ashley to become Prime Minister. Ashley's actions and appeasing attitude actually annoyed many but actuated an end to the split in Labour - Wedgwood stepped down, and former President of the Board of Education Morgan Jones did manage to find a middle ground.
[4] Lord Wolmer (later to be the 3rd Earl of Selborne, the first Prime Minister to not accede to his peerage during his premiership since, well, Lord North) took over after Ashley's sudden resignation due to ill-health. The already fragile Peacetime Coalition broke down.
[5] Morgan Jones had unexpectedly died at only 53 earlier that year; many had doubts about caretaker leader Arthur Greenwood and former Home Secretary George Isaacs ended up being his main challenger and subsequent Labour leader. His victory over Wolmer was somewhat unexpected - and when war finally broke out that year Isaacs was manifestly unprepared. Conservatives were reluctant to form a wartime coalition with someone with such strong trade union ties - and Isaacs was thus couped in favor of his Secretary of State for War, a man who had been right about the Nazi threat all along.
[6] "If the Fuhrer wants to get to Britain any time soon he's going to have to go through our navy - and me." Lord Morley smiled grimly. "Karl Wettin is about to learn the worst a Baron can do to a Duke."