Sir William Benyon: Conservative MP whose personal loyalty to Margaret Thatcher did not prevent him from taking on the Party

Bill Benyon was a serious politician, but not a man to take himself too seriously. When other politicians were declaring their favourite programmes to be Newsnight and Panorama, he was declaring a love of The A Team, Happy Days and Basil Brush. In many ways he remained the naval officer he had been in his formative years, conscientious, decent, God-fearing, always ready to serve and to respect his fellow men.

In his constituency of Milton Keynes he was thought a great gentleman and he was known to spend countless hours in village halls and community centres holding surgeries to help solve his constituents' problems. He came to national politics as a member of the Monday Club and a supporter of Enoch Powell over immigration, but for most of his time in the Commons he was a One Nation Tory who regularly clashed with Margaret Thatcher while remaining deeply loyal to her personally. When she was challenged for the leadership by Michael Heseltine, he was unwavering in his support. Many of their clashes were over local government since he was a staunch defender of its independence.

In 1977 he won a second reading for his bill to amend the Abortion Act in the teeth of opposition from ministers in the DHSS and the Leader of the House and he battled long and hard in an effort to get it through the committee stage. The Government was determined to see it fail, and it did. Undeterred, he went on to co sponsor the Corrie bill and support other efforts to amend an act which he thought had been badly abused. He was more successful with his co-sponsorship of Frank Allaun's bill to impose a right of reply on the media, but perhaps his most successful campaigns were among of the earliest: the defeat of the Roskill Commission's proposal that London's third airport should be at Cublington, and his ongoing campaign for Milton Keynes, the new town whose establishment he had favoured and which he chose to represent rather than leafy Buckingham.

He was born William Richard Shelley, eldest son of Vice Admiral Richard Shelley and Eve Gascoyne-Cecil, granddaughter of the 3rd Marquess of Salisbury, three-time Prime Minister. While his background was landed gentry, like his father he had to make his own way in life. At 13 he became a cadet at the Royal Naval College, Dartmouth and served in the Navy until 1956, reaching Lieutenant and spending some time as ADC to the Governor in Kenya during the Mau Mau rising.

He left the Navy for Courtaulds, staying until 1967. By then he had become heir to a potentially rich estate. His father's second cousin, Sir Henry Benyon, had no heir and left the estate to the Admiral on condition that he took the name of Benyon. The estate comprised some 14,000 acres on the Berkshire-Hampshire border and some 300 houses in De Beauvoir Town, Hackney. It was subject to 85 per cent death duties; most of the houses were without sanitation and the estate was badly run down, His father was in poor health and so the task of paying off the death duty and rebuilding the fortunes of the estate fell to Bill. With judicious management, some luck and the odd land sale he was able to modernise the whole estate and even add to it, before putting it in trust for his family.

He was drawn into politics by way of the Rural District Council and from 1964-74 membership of Berkshire County Council. He was adopted to fight Buckingham in 1967 and at the 1970 Election captured it from Robert Maxwell.

No sooner had he been elected than the Roskill Commission nominated Cublington as the third London airport, and Benyon led the successful campaign to kill off the project; he was delighted when the Government chose Foulness. He was not averse to major development, however, as shown when he gave his support to the idea of a new city in the countryside and furthered the cause of Milton Keynes.

In May 1972 he became PPS to Paul Channon, Minister for Housing. Boundary changes had made his seat vulnerable, and Maxwell was determined to recapture it. Benyon beat off the challenge in February 1974 and Maxwell responded by attempting to restructure the troubled firm of Aston Martin as a workers' co-operative. Both men knew that this would attract aid from the Labour Government, and writs flew when Benyon disclosed the firm's position at a press conference and was accused of breaching a confidence.

Benyon beat Maxwell for the third and last time in October 1974. He had been made a Conservative whip in July, but left the whips' office in November 1976 to promote his bill to amend the Abortion Act. Although he was able to secure a second reading, after eight months of bitter debate it was, in effect, killed.

Although Thatcher and he seemed to have a considerable regard for one another – she wrote him a three-page letter of sympathy when he was mugged – it was obvious to the whips that Benyon was not "one of us". He was soon involved in a series of votes against the Government. One cause of discontent was the desire to hobble local government spending, the other his dislike of cutting or taxing benefits.

He helped foil Heseltine's desire to make rate increases dependent on a referendum and was successful in opposing parental contributions to tuition fees. He was a proponent of a smaller GLC and an opponent of the poll tax.

The whips could not prevent him from being elected to the Executive of the 1922 Committee but they did prevent him from becoming chairman. In 1985 he backed Francis Pym's abortive attempt to launch Centre Forward, and became Chairman of the One Nation Group in 1986. He threw himself into making Milton Keynes a success, welcoming the decision of the Open University to make its home there.

Faced with a choice of constituency once the growth of Milton Keynes made it inevitable that it would be hived off from Buckingham, he defied everyone's expectations by choosing not to fight the safer seat. He won Milton Keynes in 1983 and 1987, but called it a day when the new constituency was itself split into two. On leaving the Commons, Benyon chaired the Peabody Trust (1993-98), making full use of his knowledge of social housing.

William Richard Shelley (William Benyon), Naval officer and politician: born 17 January 1930; MP for Buckingham 1970–83, Milton Keynes 1983–92; Kt 1994; married Elizabeth Ann Halifax (three daughters, two sons); died 2 May 2014.