As minister for foreign affairs and a likely future Taoiseach, Dr Patrick Hillery impressed the British embassy in Dublin which profiled him in advance of a meeting with Sir Alec Douglas-Home and William Whitelaw in April 1972.
The profile is contained in British cabinet papers released this week.
"Dr Hillery is regarded as a powerhouse for ideas, one of the few members of Fianna Fáil who has new policies and is eager to implement them.
"The greatest example of this has been in his present job, where he has perforce concentrated on Anglo-Irish relations and, in particular, the North. Policy in this field is determined primarily between him and the Taoiseach; and it is likely that the Fianna Fáil new line on the North owes much to Dr Hillery.
"This line is that reunification is a long-term problem between Irishmen and that the Republic should seek to influence events in the North through HMG [Her Majesty's government] and not directly.
"Nevertheless, Dr Hillery is probably less pliable than Mr Lynch and, were he Taoiseach, would perhaps be more insistent that HMG should take sterner action with right-wing unionists in the North.
"The Republican experiences of his youth have thus had surprisingly little influence upon him, though he is committed to work for reunification and would claim to be a Republican.
"It is noticeable that his relations with Messrs Blaney, Boland and Haughey remain cordial. (He has said in public that he would be glad to see Mr Haughey back in the Cabinet.)
"It is said that he has taken care not to fall out with these men because he hopes to be the next Taoiseach. He has been connected with no party faction and, despite the events of 1970, has retained a remarkably uncompromised position in the leadership.
"He would thus, it is said, be able to hold the ring between the rivals, Mr Haughey and Mr Colley, yet not be the obvious compromise candidate which Mr Lynch was in 1966.
"Dr Hillery has a pleasant manner. He can appear diffident and casual but has an undoubted intellectual capacity and a strong will; since the government crisis of 1970 he has appeared much more assured - even brash - and has handled the Dáil with confidence.
"He has wrought great changes in the Department of External Affairs, which has suffered as a result of 12 continuous years under Frank Aiken.
"In particular, he is trying to establish relations between the Department of External Affairs and the press, which have hitherto ignored each other. He is very popular with his civil servants. Once his initial reserve has been broken down, he is an easy and amusing Minister with whom it is a pleasure to do business.
"Dr Hillery is a keen swimmer and golfer. He speaks some French. Having found that he sleeps better without taking alcohol, he now normally abstains."
Another Foreign Office briefing paper says Dr Hillery's personal position over Northern Ireland has, since mid-1971, been "somewhat ambiguous".
"Before that date, he was one of the doves, supporting Mr Lynch. From mid-1971 onwards there were clear signs that he wanted to detach himself from Mr Lynch; he was happy to seem to be fully occupied with the EEC negotiations, for that kept him clear of the Northern Ireland crisis at a time when he apparently expected Mr Lynch to fall through the failure of the latter's 'peaceful policy'.
"Dr Hillery may have hoped that he would be Mr Lynch's respectable if more nationalist and more hawkish successor.
"However, there are now signs that, after HMG's initiative [direct rule] he is again falling into step behind Mr Lynch whose domestic position has become stronger. "The Irish Ambassador [IN LONDON]has said that Dr Hillery is coming very much under instructions from Mr Lynch."