One of the reasons why Seán Lemass has been celebrated by various biographers is because by the time he became taoiseach in 1959, he was determined to force the pace of change and did so in ways that are regarded as having inaugurated modern Ireland. This, in Tom Garvin's words, was because of his devotion to "politics of the practical and rhetoric of reality".

Garvin's admiration for Lemass shines through this handsomely illustrated book, and it is the author's insight into the psychology of politicians and political change that punctuates the wise, insightful and lively text. Garvin's vivid writing style and his refusal to be cautious in his assessments have always marked him out as a provocative, original scholar.

Lemass did not leave behind a substantial personal archive and the Royal Irish Academy has compensated by using images and documents from a variety of different sources to complement Garvin's text. The result is more than impressive and is an indication of the publisher's determination to present history in a lavish and accessible way while not compromising on intellectual integrity.

Lemass was shy, gruff, and impatient, often appeared intimidating and had a "quite obvious disregard for rural ways and society". He was a champion of private enterprise "while having a radical streak in the form of respect for the worker".

He also overcame his poor public speaking abilities to the extent that by 1959, a confidential personality report on him prepared for the British embassy suggested his speeches were "well-pondered and well-expressed". He also had a "passionate obsession with economic development". As minister for industry and commerce in the 1930s, Lemass lost his initial enthusiasm for tariff-driven development at a relatively early stage, but the Second World War stymied his desire to engineer a new, free- market approach.

It's estimated that 1,000 new factories were built during the 1932-'48 period and some 80,000 jobs created, but many of them were also local monopolies "protected by legislation essentially devised by him". The policies adopted by Lemass left behind a lot of parasitical bodies and quangos; his policy of economic protection left "a legacy of golden circles that had privileged access to power and contractual preference… incorruptible, he left room for the corrupt".

In relation to political practice – and it seems important to emphasise this given the frequency with which Fianna Fáil's contemporary leaders evoke his name as the ideal role model to follow – Garvin suggests Lemass was "almost haunted by the pervasive personalism of Irish political culture and went out of his way to try and set a counter example by his own personal behaviour".

He was also capable of speaking out of both sides of his mouth about private enterprise and labour, and Garvin sidesteps some of the arrogant and autocratic tendencies that sat uncomfortably alongside his "extraordinary record in Supplies during the war years".

What's most interesting about Garvin's analysis is the way in which he examines Lemass's critique of "the pathological pessimism and apathy of Irish life" that surrounded him.

As taoiseach from 1959-'66, he was able to tell his colleagues impatiently that irredentist anti-partition rhetoric could not hide the fact that Northern Ireland existed with the consent of the majority of its inhabitants. He infused his governments with young new ministers keen to impress and he insisted on endorsing TK Whitaker's plans for economic liberalisation.

That does not mean he was a masterful taoiseach; he had a rather "freewheeling approach" and tended to lose control towards the end.

Nonetheless, Garvin's conclusion is that Lemass was extraordinary in achieving "almost precisely what he set out to do in his life's work".

Those who continue to evoke his memory should not forget that he also believed in the necessity of continued spending during a ­recession.

Judging Lemass by Tom Garvin, Royal Irish Academy, €30