CONVENTIONAL wisdom has it that the golden years for Chief Secretary Sir David Ford were under Lord Wilson's governorship. It is also said Sir David, who steps down on Saturday after 61/2 years in the post, took advantage of the then ''lame-duck'' atmosphere at Government House to amass power, only to have it taken back, with the advent of a more powerful Governor. Like all such stories there is a grain of truth in it. Sir David admitted, in a farewell interview with the Sunday Morning Post, that his status had changed since the arrival of Governor Chris Patten. ''There is obviously a difference in the role of the Chief Secretary which derives from the role of the Governor,'' he said. ''Under Lord Wilson there was certainly a tacit understanding, not a formal agreement, that we would share the public presentation of particularly political policy.'' But from the moment Sir David met Mr Patten in London last year - a month before he took up the Governorship - it was clear things were going to change. Mr Patten offered to ''bear more of the load'' on the political front and, within a week of arrival, took direct control of the Government's high-powered public relations group, previously the Chief Secretary's personal domain. Yet Sir David insisted he did not resent this loss of power and had happily reverted to acting like a more traditional chief secretary. ''I certainly haven't found that in any way uncomfortable and I don't think the Governor has either,'' he said. ''Clearly he was used to that style, and I was obviously quite comfortable with that change. I have, after all, worked with ministers in the UK before so it's nothing new to me.'' Nor is there any sign Sir David's overall influence has waned despite the advent of a more hands-on Governor. Although partly out of the loop on the political front, as Mr Patten instead has dealt directly with the like-minded Secretary for Constitutional Affairs Michael Sze Cho-cheung, Sir David was given such a free hand to continue running the civil service his way, that some senior officials moan about the extent of the Governor's hands-off policy. In the 17 months he has been at Government House, Mr Patten is understood to have accepted every civil service appointment recommended to him by Sir David, and apparently left the Chief Secretary to decide the timing and manner of his departure. No wonder then, that Sir David was quick to note how - while his public profile may have faded under the new Governor - his policy role has not. Any change has ''certainly been in terms of presentation and not in any way in my role as the Governor's mainadviser'', he said. Those close to both say Sir David has actually found it easier to work with a ministerial-like Governor than his Foreign Office predecessor. Certainly there have been none of the reports of tensions, that characterised the final years of the Wilson tenure. He has also seamlessly managed the transition from attacker of advocates of faster democracy, during Lord Wilson's days, to supporter of the Patten package to expand the franchise in 1995. Like British officials, he prefers to describe the apparent U-turn on the democracy issue as ''an evolution of policy rather than a change''. But the man who, only a couple of years back, was preaching the ''gospel of caution'' when it came to direct elections, has no trouble explaining how and why the present system is inadequate. ''There has been considerable criticism of the way in which the functional constituencies were too narrowly based,'' he said. ''The very nature of functional constituencies . . . is an unusual notion and one which is not easy to make credible, particularly once you've dealt with the most obvious professions and economic groups.'' Colleagues say the chief secretary began talking of the need to make the electoral system more credible long before Mr Patten's arrival. Sir David dates the roots of the present policy to the events of June 1989 - when Hong Kong dramatically demonstratedits support for more democracy. ''The development of our political system has been something which has been ongoing ever since we reached agreement with the Chinese over the Joint Declaration, and we have tried to make the speed at which it evolved reflect the mood in the community,'' he said. ''That was certainly true after the events of Tiananmen Square when there was a strong feeling we needed to have a more representative independent Legislative Council . . . so we tried to respond and I think the Governor's and our thinking on functional constituencies and the Election Committee is an extension of that feeling.'' Certainly Sir David had long predicted the negotiations over the 1994-95 polls would be tough, and that Beijing might demand a price for a through-train which was too high to pay. ''We recognised for many years that these were not going to be easy discussions,'' he said. ''We were going to want to introduce a fair and open system with substantial electorates and there has been . . . a reluctance by the Chinese to see that natural development.'' Now, Sir David uses that foresight to support his contention Britain's present policy on the issue is consistent with its previous one, stressing - as the Governor has done of late - that the Patten proposals for the 1995 polls are far from radical, and unlikely to result in a vastly different Legco. ''I don't think what we're suggesting is by any means revolutionary. It's evolutionary. It's not going to produce a Legislative Council which is radical,'' he said. ''The idea that we will somehow destabilise Hong Kong by producing a different Legislative Council seems to me to be quite absurd, and it seems to me a very sad reflection on the judgment of Hong Kong people [to say] they would wish to elect into the Legislative Council people who would in any way destabilise Hong Kong.'' That evolutionary process will continue far beyond the forthcoming elections and, Sir David believes, may lead to some of the developments he has long advocated. He has repeatedly spoken of the need to bring legislators more closely into the Government's decision-making process yet participated in events that have pushed them further away, with the separation of membership of the Executive and Legislative councils last year. But Sir David believes the time for that may come after the 1995 polls, when even the possibility of some form of coalition cabinet might have to be considered. ''One option, and one option only, would be for us to form an Executive Council which was a reflection of the Legislative Council in terms of its membership,'' he said. ''It's difficult to know at this point in time whether that's workable, whether we could find members of the Legislative Council prepared to abide by the principles of confidentiality and collective responsibility which are essential to the working of any cabinet. ''But it's not impossible, and it's not impossible that the various parties and groupings which are represented in the Legislative Council after the 1995 election will be pushing for that sort of system.'' Any such move would mean reversing last year's separation of the membership of the two bodies, a move which the Governor and his aides have repeatedly stressed is a temporary measure. It would also infuriate Beijing - which is likely to see it as a threat to Hong Kong's executive-led system of government, and a backdoor route to power for the likes of Mr Martin Lee Chu-ming. Yet, even if it happens, Sir David will not be here to see it. He leaves on November 29 to take up the post of Commissioner to London, more than a quarter of a century after arriving at Kai Tak. However, Hong Kong is unlikely to have seen the last of him. After he completes his three-year posting to the London office in 1996, Sir David wants to retain some connection with the territory - and hinted he might live here again.