Baroness Denton of Wakefield, the first woman minister to serve at the Northern Ireland Office, died today, aged 65.
She had been suffering from cancer.
The new Northern Ireland Secretary John Reid said: "All those who worked with her will remember the energy, commitment and enthusiasm that she brought to her role in Northern Ireland.
"Northern Ireland has much to be grateful to Jean Denton for."
The Tory peer, who died in London, was for three years part of Sir Patrick Mayhew's team at Stormont, dealing with agriculture, health and the economy.
She was well regarded, particularly on tourism issues, but her time in Belfast was marred in l997 over claims of sectarian harassment in her office - allegations which she rejected outright.
She was criticised for violating fair employment guidelines by transferring a civil servant who made the complaint, rather than the person who had been the subject of it.
Even some of her opponents felt she had been harshly and unfairly treated, but she was damaged when she left Northern Ireland after Labour's victory the same year.
The Fermanagh-south Tyrone Ulster Unionist MP Ken Maginnis said: "She was someone who brought no political baggage to the job, and came to Northern Ireland of her own violation and with very firm ideas as to how she wanted to improve the economic climate.
"She had scant regard for red tape and bureaucracy and more interested in getting the job done rather than standing on ceremony."
Minister of State Adam Ingram, who took on her role when he moved to Belfast with Dr Mo Mowlam after Labour's victory, said: "Many of the initiatives she started I was able to build upon and now the Assembly is building upon. Her contribution was important to the quality of life in Northern Ireland."
The Baroness was diagnosed with cancer in l997 and had an operation for a brain tumour later that year.
PA