Image caption 'The most important Englishman in the politics of Wales since Mr Gladstone' - Lord Callaghan of Cardiff

If you're interested in politics and have a spare hour, you could do a lot worse than watch this lecture on the last Welsh MP to occupy 10 Downing Street.

Jim Callaghan, who died in 2005 aged 92, was a Cardiff MP between 1945 and 1987 when he went to the House of Lords.

He became prime minister 40 years ago this year and is the only politician to hold the four "great offices" of the British state - PM, chancellor, home secretary and foreign secretary.

His biographer, historian and Labour peer Kenneth O. Morgan, used his lecture in Speaker's House, to remind his audience of Callaghan's childhood poverty. His father died when he was nine years old and his mother had no pension.

"They were very, very poor," said Lord Morgan. "They were reliant on bread and margarine supplied by the Baptist Church.

Morgan recalled Callaghan's time in government and how "pivotal" Northern Ireland was to his career.

On Europe, he was "something of an agnostic" - but as foreign secretary he took on the renegotiations of Britain's membership ahead of the 1975 referendum with zest. "How much he achieved is very debatable," acknowledged Lord Morgan.

He argued that Callaghan was seen as an effective prime minister until the end of the summer of 1978 when a series of errors damaged his reputation.

'A rare PM'

Callaghan returned from a summit in Guadeloupe to be greeted by waiting reporters. 'Crisis? What Crisis?' became one of the defining front pages of his time in No 10, even though he had not used the phrase.

"Jim himself believed it wasn't an unfair account of what he had said," said Lord Morgan, who thought he had been "clearly niggled by a young journalist whippersnapper".

He became the first prime minister since the Duke of Wellington to resign after losing a vote of confidence but Lord Morgan argued that he was the best since Clement Attlee.

"He was a rare prime minister," he said. "His standing was higher when he left office than when he entered 10 Downing Street."

According to Lord Morgan, Callaghan was "the most important Englishman in the politics of Wales since Mr Gladstone".

The first devolution referendums in Wales and Scotland were held during the dying weeks of his premiership: "He pressed on with devolution although I know from my own experience he wasn't keen on devolution."

The historian also recalled conversations with the "English patirot" about rugby: "When Jim talked about 'we', he meant Wales".

Not everyone will share Lord Morgan's favourable view of Lord Callaghan's record, but the lecture is worth catching on the BBC iPlayer while you can.