Slaughter and May corporate partner Susannah Macknay is set to leave the firm's London office for Australian heavyweight Gilbert + Tobin, in a rare departure for the Magic Circle outfit.

Macknay has been at Slaughters since 2007 when she joined as an associate. She was promoted to partner seven years later and has acted on a series of major deals during her time at the firm.

She counts Vodafone as a major client, advising it on its deal to merge Dutch operations with U.S. cable giant Liberty Global's to create a Netherlands-wide communications provider in 2016, and the following year when it bought the majority of Liberty Global's European assets for €18.4 billion.

She also advised French financial services group Oddo & Cie on its sale of London-headquartered wealth management company Kleinwort Benson to French bank Societé Générale in 2016.

A spokesperson for Gilbert + Tobin said in a statement: "Gilbert + Tobin are delighted to announce that Susannah Macknay, currently a partner at Slaughter and May in London, will be joining their market-leading M&A/corporate team in Melbourne later this year, when she returns to Australia."

The two firms have a collaborative working relationship, and a person at Slaughters said Macknay will continue to work closely with the team.

Slaughters rarely sees partners leave and seldom adds lateral hires.

Last year disputes partner Mark Hughes quit the elite firm's Hong Kong office to join Eversheds Sutherland in a blue-moon departure for Slaughters.

In 2017 the firm made history with its second-ever lateral partner hire, with the addition of Herbert Smith Freehills pensions head Daniel Schaffer.

The hire was its first lateral recruit for London after it recruited Hong Kong corporate partner John Moore in 2014 from Morrison & Foerster.