Gordon Brown has described his struggles to communicate with voters in the era of "touchy-feely" politics and social media.
In his memoir, published a decade after he became prime minister, Mr Brown acknowledges he had not been "an ideal fit" in an age which put personal politics to the fore.
However, he says that while he may have been seen by some as being remote or aloof, what mattered to him throughout was "what our government could do for our country".
In a first extract from My Life, Our Times, Mr Brown admits his "biggest regret" as prime minister was his failure to convince voters to back his vision of progressive politics following the global financial crash of 2008.
Throughout his time in No 10, Mr Brown was criticised for being dour and awkward in public - factors widely seen to have contributed to his general election defeat in 2010.
In the book, he describes growing up in an era where "reticence was the rule" and politicians were considered "self-absorbed and even out of touch" if they were "constantly self-referential in public".
It left him, he says, uncomfortable about being "conspicuously demonstrative" - one of the reasons why it took him so long to write his memoir.
"During my time as an MP I never mastered the capacity to leave a good impression or sculpt my public image in 140 characters," he writes.
"In a far more touchy-feely era, our leaders speak of public issues in intensely personal ways and assume they can win votes simply by telling their electors that they 'feel their pain'.
"I fully understand that in a media-conscious age every politician has to lighten up to get a message across and I accept that, in the second decade of the 21st century, a sense of personal reserve can limit the appeal and rapport of a leader.
"I am not, I hope, remote, offhand or uncommunicative. But if I wasn't an ideal fit for an age when the personal side of politics had come to the fore, I hope people will come to understand this was not an aloofness or detachment or, I hope, insensitivity or a lack of emotional intelligence on my part.
"Really, to my mind, what mattered was not what I said about myself, but simply what our government could do for our country."
While he helped to secure a worldwide recovery plan following the crash, Mr Brown says his inability to communicate more effectively meant he was unable to persuade voters to back his vision of the way forward.
"My own biggest regret was that in the greatest peacetime challenge - a catastrophic global recession - I could not persuade the British people that the progressive policies I pushed for, nationally and internationally, were the right and fairest way to respond," he writes.
"We won the battle - to escape recession. But we lost the war - to build something better. I fell short in communicating my ideas. I failed to rally the nation around the necessary fiscal stimulus and my plans for radical change."
:: My Life, Our Times by Gordon Brown is published by The Bodley Head on November 7.