Jim Devine had been Mr Cook's agent since 1983

Jim Devine will defend a Labour majority of more than 13,000 votes in the Livingston constituency.

The Liberal Democrats have chosen Charles Dundas as their candidate, and the Scottish National Party have selected Angela Constance.

Mr Devine is an official with trade union Unison.

He was best man when Mr Cook married his second wife, Gaynor.

'Great privilege'

He had been Mr Cook's election agent since the 1983 general election and has held several key positions in the Labour Party in Scotland.

No date has yet been set for the by-election caused by the death of Mr Cook at the start of August, while on a walking holiday.

Mr Devine said: "I am obviously delighted and honoured to be selected by my political peers.

"It is a great privilege to represent the community in which you were born and brought up."

He went on: "I will never, ever, be Robin Cook.