Shortly before taking to the water Mr Oldfield, who was apparently privately educated before studying at the London School of Economics and is a Fellow of the Royal Society of Arts, posted a manifesto online.
Entitled Elitism Leads to Tyranny, he declared: "This is a protest, an act of civil disobedience, a methodology of refusing and resistance.
"This act has employed guerrilla tactics. I am swimming into the boats in the hope I can stop them from completing the race."
In his manifesto, Mr Oldfield said he was targeting the boat race because of its elitist nature – saying it went past Fulham Palace, a former royal residence, St Paul's, the leading public school, and the London home of Nick Clegg, the Deputy Prime Minister, who he attacked for being educated at public school.
He even likened it to the actions of Emily Davison, the suffragette who threw herself under the King's horse at the Epsom Derby on June 4, 1913 and died of her injuries four days later.
Mr Oldfield is familiar with this stretch of the Thames, having once worked as a coordinator for the Thames Strategy project, set up to regenerate the landscape around the river from Kew to Chelsea.
He is also a member of a group of activists called This Is Not A Gateway, which he set up with his girlfriend, Deepa Naik, a fellow artist, to protest at the way modern cities are run.
Mr Oldfield, who lives in a 1930s apartment block in Whitechapel, east London, also objects to "shiny buildings" and wants to "remove every fence from around every park".
His blog urges people to stage similar stunts in a bid to disrupt the London Olympics and suggests, somewhat bizarrely, that taxi drivers take their passengers the slowest and most expensive route possible in protest at their "elite status".
Last night, he was being widely mocked on the internet, the medium he used to post his manifesto – although his actions are being more seriously studied by the organisers of the Olympics.