Sarah Wykes is Senior campaigner for Global Witness working on corruption and mismanagement associated with oil revenues. I've worked with Sarah. She's committed to this cause for the benefit of the ordinary people of Africa, where she she has done much of her work.

On Sunday Sarah was arrested in Angola and charged with espionage. I am certain she has done no such thing. Diplomatic effort yesterday has led to an assurance that she may be released on bail, but this is dependent upon the attorney general of Angola agreeing.

Global Witness has demanded that Sarah have access to her own lawyers in Angola, that she be unconditionally released, that the Angolan government apologise for her mistreatment and that the UK government and others work for her release. So do I.

If this situation develops I hope others might support Sarah's cause. Campaigning always imposes a cost: this is too high a price to pay when you're asking for accountability.