Cowen was born at Stella Hall, Blaydon, son of Sir Joseph Cowen who worked on the River Tyne commission for many years and was MP for Newcastle 1865-73. Cowen junior was educated privately in Ryton and Edinburgh University, where he interested himself in European revolutionary movements.
Cowen then joined his father in his Blaydon brick business, smuggling documents abroad in the consignments of bricks. Cowen numbered among his guests and friends Mazzini, Garibaldi, Kossoth, Louis Blanc and Ledru-Rollin, as well as Herzen and Bakunin. His purse assisted them and his pen advocated their cause. In 1862, Cowen was secretly building a warship on the Tyne for use in the Polish insurrection, and almost certainly conspired to assassinated Louis Napoleon. Such was his reputation that one poor political refugee, stranded in the London docks knew no other words than: 'Want Mister Cowen... Newcastle.' At home, Cowen sympathised with the aims of the Chartists and worked on their behalf.
Cowen from boyhood was a contributor to the Newcastle Chronicle, of which he became the proprietor and editor in 1862. He also founded the Tyne Theatre and Opera House in Newcastle in 1867. Cowen became Liberal MP for Newcastle in 1873 and was complimented on his maiden speech by Disraeli. Gladstone, the leader of his own side, let it be known that he thought Cowen's style too rhetorical, smacking of Macaulay. Cowen did not disguise his accent in parliament, and this endeared him to his constituents. He dressed there like a North East miner in his Sunday best, a novelty then in the House of Commons.
Cowen was not a straight party man, and his independence sometimes got him into hot water. Though his wealth opened many doors, he was averse to society. His populist radicalism espoused the North East as the birthplace of liberty and the cradle of industrialisation - and he always insisted that the two achievements were not separate. Cowen, the 'Blaydon Brick' recognised that the people of his region were the makers of wealth and the bearers of his hopes. He and his working-class allies refused to accept dominant versions of Englishness, where working-class people were strangers in their own country, while other people held the levers of power. A fine bronze statue of Cowen stands in Fenkle Street in Newcastle.