Mileham matriculated with academic honours from Selborne College in East London in 1988 and went on to graduate with a Bachelor of Commerce degree from the University of the Witwatersrand. He continued his studies to obtain a post-graduate Diploma in Advertising and Marketing from AAA School of Advertising. Post studies, he commenced work for , a South African advertising agency, handling brands such as Coca-Cola and 5FM. In 1996, he was employed by Coca-Cola to launch the Powerade sports drink in South Africa. In 1998 he joined Microsoft South Africa as a marketing manager, initially only covering consumer products, but later promoted to include all desktop applications for both the consumer and business sectors. In 2001, he relocated to the Eastern Cape, where he founded his own marketing and management consultancy business, Forward Momentum. Mileham has two children from his first marriage to Laura Guest. He married fellow Democratic Alliance Member of Parliament, Natasha Mazzone in July 2017.
Politics
Mileham was actively involved in party politics for the former Democratic Party as a party agent and activist during the 1994 and 1999 elections. In 2003, he became actively involved in local politics. He joined the Democratic Alliance in Port Alfred where he was soon appointed constituency chairperson. In 2006, he was elected to the Ndlambe municipal council, and appointed as the party's Chief Whip and finance spokesperson. In 2007, Mileham was selected to be part of the first class of Democratic Alliance's Young Leaders Programme In 2009, he stood unsuccessfully for Parliament. In 2011, he was elected as a municipal councillor to the Buffalo City Metropolitan Municipality, and was appointed as the DA's Chief Whip. In 2013, following the death of Pine Pienaar, a member of the Eastern Cape Provincial Legislature, the DA's provincial leader Athol Trollip elected to return to the province following his reelection defeat to Lindiwe Mazibuko for the position of DA Parliamentary Leader. The DA selected Mileham to fill the seat. Mazibuko appointed him Shadow Deputy Minister for Land Reform and Rural Development. After his re-election in 2014, Mileham was appointed the Shadow Minister of Cooperative Governance and Traditional Affairs by the new Leader of the Opposition, Mmusi Maimane. During tenure as Shadow Minister of COGTA, Mileham laid criminal charges against people involved in the VBS Mutual Bank scandal.In February 2019, he was appointed as Shadow Minister of Energy. He held this position until June 2019, when Maimane appointed him as Shadow Minister of Mineral Resources and Energy.
