How big was the IMF loan Britain received in the 1970's?

Question

During the turbulent times of the 1970's, the United Kingdom had to ask the International Monetary Fund (IMF) for a loan to meet its obligations. The National Archives state that in September 1976, a loan of $3.9 billion was requested. However, it goes on to say,

Following the agreement with the IMF, the overall economic and financial picture improved. Interest rates were soon reduced and the pound quickly appreciated in value. By the end of 1977, partly as a result of new oil revenues, there were improvements in the balance of trade. Britain did not need to draw the full loan from the IMF.

How much did Britain actually receive from the IMF, and how long did it take to pay back?

Answer 1

According to the autobiography of Lord Denis Healey, who was Chancellor of the Exchequer from 1974 to 1979, Britain only drew half of the IMF loan. Furthermore, he states that drawn amount were repaid in full by 4 May 1979, when the Labour government including himself left office.

Moreover, I drew only half of the loan offered in return by the IMF, and had repaid it all - or the equivalent - by the time I left office.

Source: Healey, Denis. The Time of my Life. London: Penguin, 1990. p. 432.