Donnelly, whose ancestry was Irish, was born in Sibsagar, Assam, India, where his father was a tea planter; his mother was English and descended from a member of the Indian Civil Service.
As a keen sportsman, Donnelly became secretary of the London Grasshoppers Rugby Club on leaving school and while working as an office boy.
Despite the general trend away from the Labour Party, Donnelly beat Lloyd George by playing on the fact that he was supporting the Conservatives, and won the seat by 129 votes.
While serving as an MP, Donnelly upped his income by acting as a consultant to the engineering firms David Brown and Philips Industries and to the merchant bankers Hill Samuel.
The final breach in relations came after spending cuts caused by devaluation of the Pound sterling in November 1967 forced the government to withdraw from defence commitments 'east of Suez'.
At a meeting of the Monday Club in 1968, Donnelly received a two-minute standing ovation, and then told members "Mr Wilson should resign and leave public life".
In some respects the party's policy was to the right of the Conservatives, advocating the abolition of the welfare state, sweeping changes to the taxation system, and the return of national service.
In addition to prolific journalism (he specialised in book reviews), Donnelly had gone into business after his defeat in 1970 and became chairman of ICPS Ltd and Managing Director of Practical Europe Ltd.[3] In the recession of 1973 and 1974, his companies struggled financially, and this, combined with his failure to get back into the House of Commons as a Conservative, was to cause serious depression.
Donnelly committed suicide in a hotel room at West Drayton near Heathrow Airport on 3 April 1974, by drinking a large amount of vodka and taking a massive overdose of barbiturates.