Jenkins joined Cooper Brothers in 1960, qualifying as a chartered accountant in 1963 gaining the 3rd Certificate of Merit.
He was a partner in Coopers and Lybrand (C&L) (later PWC) from 1969 to 1994 and became a pioneer in computer auditing both in his firm and the accounting profession generally.
During his career Jenkins served as a non-executive director of a number of organisations, including the Royal Ordnance Factories, Commission for the New Towns, Automobile Association, the Architectural Heritage Fund and London First.
Jenkins' civic career started on his election as Alderman for the City of London Ward of Cordwainer in 1980.
Elected 664th Lord Mayor of the City in 1991[8] his Mayoralty was particularly concerned in the response to the bombing of the Baltic Exchange,[9][10] the location of the future European Central Bank (ECB) and the wider impact of the Single Market.