Nikki da Costa

Nikki Da Costa is a British political advisor and activist. She was a special adviser serving as the director of legislative affairs in 10 Downing Street for two Prime Ministers: Theresa May from September 2017 until November 2018, and again for Boris Johnson from July 2019 to August 2021. She was heavily cited in the High Court case regarding the prorogation of parliament in 2019, having provided written advice to the then Prime Minister Boris Johnson that the prorogation should take place. She was named one of the 100 most influential women in the UK by The House in 2020.

Between her stints in Number 10, da Costa worked in public affairs, through the Cicero Group, and her own consultancy company. More recently, she has worked as a specialist partner with Flint Global lobbying firm. She alongside Mercy Muroki was an unpaid "Policy Fellow" to the Minister for Women and Equalities, Kemi Badenoch for 2023–24.

Da Costa has occasionally written op-eds and other articles reflecting on her time in government and giving advice. She wrote in The Times in January 2022 regarding Partygate that Number 10 had "failed as a collective" to follow the COVID-19 lockdown standards it had set.

She was the Conservative candidate in North East Hertfordshire at the 2024 United Kingdom general election. Her election bid was narrowly defeated by Labour's candidate Chris Hinchliff.