As revealed on prweek.com (24 May), Kirkbride follows in the footsteps her husband Andrew MacKay, who recently joined the lobbying arm of Burson-Marsteller.
Both Kirkbride and MacKay decided not to stand in the 2010 general election after it emerged they had claimed second home allowances that were deemed to be inappropriate. The pair, whose appeals were rejected during Sir Thomas Legg's review of MPs' expenses, were forced to repay £60,000.
Tetra Strategy is run by founders James O'Keefe, a former Labour Party staffer who went on to be public affairs MD at Good Relations, and Lee Petar, one of the founding directors of BICOM (Britain Israel Communications Centre).
The 13-strong agency was ranked 113 in PRWeek's Top 150 league table, registering 49 per cent growth in fee income over the past year.
According to its submission to the APPC register, clients include the Dubai government, AMEC, Toyota, SAP and the British School of Motoring.
In a statement, Tetra Strategy confirmed that Kirkbride, a former Daily Telegraph correspondent and BBC and ITV producer, was joining on a consultancy basis. It is understood she will work full time for an initial six-month period.
A spokesman said: 'Julie will enhance Tetra Strategy's already strong political diversity across the three main parties.'