The size of the estate was said to have surprised his family and friends. As an MP, Mr Milligan earned pounds 30,854 a year - a figure which rose to pounds 31,687 in January, the month before he died. His parliamentary salary was not supplemented by lucrative directorships.
The 45-year-old MP's body was found in February on a table at his house in Hammersmith, west London. He was naked except for a pair of women's stockings, and died of suffocation caused by wire round his neck - thought to have been an auto-erotic practice to increase his sexual satisfaction.
In his career prior to being elected as a Tory MP in 1992, he held a number of fairly senior journalistic posts but none that would have commanded a salary to explain the size of his estate.
He worked as the BBC's Europe correspondent most recently, earning pounds 30,000 to pounds 35,000. Before that, he worked for the Economist magazine, presented the BBC radio programme The World Tonight, and was a foreign editor of the Sunday Times in the mid-Eighties.
However, Mr Milligan did have a reputation for frugal living and he had no family to support.
He drove an eight-year-old car and bought his house in Black Lion Lane, an attractive corner of Hammersmith, in 1980 before property prices soared.
It is thought that he made most of his money by successfully investing on the Stock Exchange money left to him by his mother Ruth - a ballet teacher who died when he was 11. He also had several life insurance policies.
His sister, Joy Hayes, reportedly said that her brother had written his will many years ago. It divides the bulk of his estate between her, their father, stepmother, two brothers and godchildren.
He also left bequests of pounds 5,000 to Oxfam and pounds 500 to his local church, St Peter's, Hammersmith, where he often worshipped.