He has been shortlisted as one of the Liberal Democrat's mayoral candidates. Their final choice will be announced in September.

A digital marketer by day, he advises start-up tech companies working on challenges from accelerating cancer treatments to tackling climate change.

Here, Sky News looks at Mr Blackie's political background and campaign priorities as he seeks to replace Sadiq Khan.

Party: Liberal Democrats
Campaigning priorities: Focusing police on sexual assault over minor drug offences; making London green
Notable achievements: Founded the award-winning Breaking Putin's Censorship campaign

Saving elephants, fighting fake news, campaigning against Brexit

Mr Blackie spearheaded the Breaking Putin's Censorship campaign, which uses digital advertising to get independent news about Ukraine to people in Russia.

More than 400 million ads have now been shown to Russians and the campaign won at the Drum Awards for social purpose last year.

In the late 1990s, Mr Blackie spent three years working on an elephant conservation project with the Namibian government.

Mr Blackie was a fierce Remain supporter and served as an adviser to anti-Brexit campaign Best for Britain.

Political experience

Mr Blackie is a long-time Lib Dem. His first role with the party was in 1999 and he served as leader Charles Kennedy's director of research during the Iraq War.

He has been part of the Lib Dems' grassroots campaigning since 2000.

In 2012 he was the London Assembly candidate for Lambeth and Southwark and he was the Lib Dem Assembly London-wide list candidate in 2016.

Mr Blackie has been shortlisted to be the party's London mayor candidate before, but has never been selected as the final choice.

Campaigning priorities

Mr Blackie says he wants to stop police "wasting time" on low-level drug offences, such as laughing gas, and use the time to better investigate serious sexual offences.

Green priorities are also a focus. He's vowed to clean up rivers, get the city's rooftops covered in solar panels and gardens and create a new transport plan for outer London to speed up the move to low carbon transport.

He also wants to "keep London welcoming" by protecting EU citizens and helping undocumented Londoners.