I have been editing the English Wikipedia since 2005 (see my user page), and I’ve been an admin there since 2007. I’ve mostly edited articles on astronomy, local history and ships. I’ve also been contributing to Wikimedia Commons since 2006.
I co-founded Wikimedia UK in 2008. Originally a non-profit company, it was recognised as a British charity in 2011. Wikimedia UK supports Wikipedia and the other Wikimedia projects in the UK, and it is a chapter of the Wikimedia Foundation. I served on its Board of Trustees in 2008-2013 as its Membership Secretary, Chair and Secretary, during which time it grew to have a budget of around £1 million, and over a dozen staff based in London. If you read or edit Wikipedia, then you should join!
I co-originated the term ‘editathon’ (with Thomas Dalton). The first event under this term took place in January 2011 at the British Library. It has since spread world-wide!
I was a member of the Wikimedia Funds Dissemination Committee (2012-2014, 2015-present). This committee provides recommendations on budget requests from Wikimedia organisations to the Wikimedia Foundation; it recommends funding of around $6 million per year.