FORMER Hong Kong minister Lord Caithness had developed a close relationship with a leading political hostess in the months leading up to his wife's suicide. The Countess of Caithness was said to be increasingly worried about the couple's finances, it emerged yesterday. The Earl, who resigned as Transport Minister on Sunday following the death of his wife, had developed a close friendship with Jan Fitzalan-Howard, 44, a former secretary to both Princess Anne and Princess Michael of Kent. She has spent 15 years working for the Tory Party, most of them with image-maker Sir Gordon Reece. According to family friends, the Countess feared their marital problems would soon become public knowledge. The turmoil in the Oxfordshire household came to a head over Christmas when it is claimed she told the Earl to leave home after he made a clean breast of his links to Mrs Fitzalan-Howard. The family relationship deteriorated and she became highly emotional. On Saturday night, Diana shot herself. The Countess' mother, Molly Coke, said she wanted the full truth about her daughter's death to come out. Mrs Coke said she was aware of gossip and added: ''I'm very interested to see if Westminster will put out a cover-up.'' The developments in the Caithness affair have deepened the crisis facing John Major's government. Mr Major returned to the Commons yesterday with the task of trying to revive his Government's credibility after the Tim Yeo scandal, the resignation of Alan Duncan, a Parliamentary Private Secretary over a council house sale deal, the controversy over MPDavid Ashby who admitted sleeping with another man over the Christmas holiday, and the future of his heavily-mauled ''Back to Basics'' campaign of attempting to raise public morality. Education Secretary John Patten said he could not remember a time during his 15 years in the Commons when things had been so difficult. But yesterday Conservative Party chairman Sir Norman Fowler strongly defended the Back to Basics policy saying the Government had never set out to preach. He said adultery didn't necessarily mean a minister needed to lose his job and each case should betreated on its merits. ''It needs to be considered on a case-by-case individual by individual circumstance. How it affects that individual's job. You can envisage circumstances where it could affect the individual's job. In other cases it does not and so I think it would be wrong and foolish to put down general inflexible rules in this area.'' A post mortem on Monday found the Countess shot herself although no suicide note was found. All the family are believed to have been been present at the house when the tragedy occurred. Their five-bedroom house had been up for sale last autumn. The friendship between Lord Caithness and Mrs Fitzalan-Howard is believed to have begun soon after the Tory election victory in 1992. Her marriage to Guards Lieutenant-Colonel Tom Fitzalan-Howard- a nephew of the Duke of Norfolk - ended 15 months ago. They have two children, aged 14 and 11. Friends described her as bright and vivacious, a superb organiser and an excellent hostess. Mrs Fitzalan-Howard and the Earl were often seen together at official dinners and receptions, where some guests assumed she was acting as his personal assistant. She was the daughter of a Royal Navy captain, married into the most prominent Catholic family in the land and was used to aristocratic circles. In 1974, she and a friend were subjected to an assault by a knife-wielding intruder at their Chelsea flat. Lord Caithness is said to have been a constant visitor to her flat in south-west London which she left recently. A porter at the flats commented: ''They looked as though they were fond of each other. They were sometimes holding each other, one arm around the waist - something like that. They always left together.''