In his political life he was 'a champion of moderate Conservatives' – but Lord (Jim) Prior, who has died aged 89, was always happiest when at home on his Suffolk farm.

Prime minister Theresa May last night led tributes to man who spent 28 years as a Suffolk MP – first for Lowestoft and then the newly-created constituency of Waveney, before serving 30 years in the House of Lords.

He is described as the 'wettest' of Margaret Thatcher's cabinet ministers, and became known for his frequent disputes with her, particularly over his less strident attitude to the trade union as employment secretary.

His long tenure as Northern Ireland secretary – where he was sent to remove him from the economic policies and decisions of government – was praised by Mrs May who described how he sought to re-establish devolved government and was part of the long line of people who worked to bring peace.

James Michael Leathes Prior was born in Norwich on October 11, 1927.

He was the second son and youngest of four children born to his father Charles, a successful country lawyer. His mother, Aileen, who was said to be an active woman with a social conscience helped shape his liberal views.

He was educated at Charterhouse and Pembroke College, Cambridge, where he obtained a first-class degree in estate management.

He carried out his National Service as an officer in the Royal Norfolk Regiment in Germany and India. After that, he took up farming, working 350 acres in Suffolk. He was on a tractor when he was asked to stand as the MP for Lowestoft.

Prior was elected to Parliament in 1959, serving that constituency until 1983 and Waveney from 1983-87.

His first promotion came in 1963 when he was parliamentary private secretary (PPS) to the president of the board of trade, Lord Erroll. Two years later he became PPS to Edward Heath, then leader of the opposition.

When Heath won power in 1970, Prior was minister of agriculture for two years and leader of the house for the next two.

After Heath's downfall, Prior stood for the party leadership in 1975, but secured only 19 votes – the same as his bitter enemy, the then Sir Geoffrey Howe – to Thatcher's 146.

Lord Deben, a personal friend of Lord Prior for 50 years – and as John Gummer represented the neighbouring seat of Suffolk Coastal, described his former boss (he was his parliamentary private secretary when he was an agriculture minister in the 1970s) as 'one of the nicest and most genuine people you could ever meet – a champion of moderate Conservatives.'

He added: 'He fought for his moderate views. He could be tough when he needed to be, but he always knew you had to bring people with you and he would not put up with intolerance.'

He said that his friend was always happiest when at home on his Suffolk farm: 'The first time I stayed with him he had to go out because a bullock had run off – that was Jim all over, he loved taking care of the farm.'

David Porter, who succeeded him as Waveney MP in 1987, said Lord Prior was 'an inspiration, a towering figure in the community but also a man of the people'.

He recounted how his predecessor had sent his wife Sarah a bunch of flowers as the 1987 election begun, knowing the pressures that were coming her way as a candidate and then MP's wife.

'He was pro-EU while I took the opposite view and we'd often discuss that, along with thousands of other political ideas.

'In government he was regarded as a safe pair of hands, being given the difficult challenge of trade union reforms among others.

'I would say he was also a courageous politician, shown most when he was Northern Ireland secretary.

'His love of the people, issues and business of East Anglia in particular crossed party boundaries and earned him the respect of and endeared him to people from every walk of life.'

Current Waveney MP Peter Aldous described his death as the 'end of an era'. Before his death Lord Prior was one of the few surviving politicians to have served in both the Heath and Thatcher governments.

Sir Henry Bellingham, the MP for North-West Norfolk, said he had been 'unbelievably helpful and courteous' to new MPs when he joined the House of Commons in 1983 and was a 'tower of strength across East Anglia'.

He praised Lord Prior's work in Northern Ireland at an 'incredibly challenging and difficult time' and credited him with securing the precursor to the Good Friday Agreement.

Sir Henry said he would be missed in Northern Ireland for his 'tact, understanding and patience', and said he had been admired right across the political communities.

Lord Prior left the House of Commons at the 1987 general election when he became a life peer. He then undertook a business life. He had been chairman of the General Electric Company since his departure from the Northern Ireland Office and served in various offices with Barclays Bank.

He was a keen sportsman and played football for Norwich City and cricket for the MCC and a number of other clubs.

Lord Prior had three sons and a daughter with wife Jane. Their eldest son, David, served as Conservative MP for Norfolk North from 1997-2001 and was made a life peer when appointed a health minister in David Cameron's government in 2015, a position he maintains under Theresa May.