It was Harold "White Hot" Wilson who devalued the pound, Peter. November 1967, the pound was devalued by 14% from $2.80 to $2.40 (happy days!!)
This bit of fiscal chicanery was accompanied by Wilson's now famous speech which was probably the first undisguised attempt by a politician to treat the electorate as complete idiots:
"It does not mean that the pound here in Britain, in your pocket or purse or in your bank, has been devalued."
"Sunny" Jim Callaghan was Chancellor of the Exchequer at the time. He had consistently opposed devaluation. He stayed in the job long enough to participate in the debate on the measure and then resigned on what he said was "a point of honour". However his "resignation" simply saw him move to replace Woy Jenkins as Home Secretary.
The Labour administration did not survive for twelve years after that. In between Ted Heath's government ruled from 1970 to 74. Wilson returned as Prime Minister in a Hung Parliament until 1976. Sunny Jim then became prime minister in 1976. It was during this time that he presided over yet another economic crisis culminating in the famous "Winter of Discontent". I can still picture him to this day, stepping off a plane in January 1979, looking tanned and well after attending a "summit" in very agreeable surroundings in Guadeloupe. (Strange they don't hold summits in Manchester in the Winter). At the time bodies lay unburied in mortuaries and rubbish was piled in the streets. The middle of London's Leicester Square (near to where I worked at the time) was six feet deep in festering filth. When asked how he was going to tackle the mounting chaos he replied "I don't think that other people in the world would share the view that there is mounting chaos." The front pages the next day were filled with pictures of him disembarking his aircraft under such headlines as "Crisis? What Crisis?" His fate was duly sealed.
At the end of March his government lost a vote of no confidence by one vote and in the following general election in May Mrs T swept into No. 10. The rest, as they say, is history.