A decorated Metropolitan police superintendent convicted of possessing a child abuse video has formally asked the court of appeal to strike down her conviction.

Lawyers for Robyn Williams, 54, this week lodged the appeal against the guilty verdict reached by a jury after a controversial investigation and prosecution, that now sees her treated like a child sex offender.

Williams was convicted in November after her sister sent her unsolicited video of a child being abused in February 2018, wanting the paedophile behind it hunted down and caught.

The Met police want to dismiss Williams from the force under a fast-track procedure that could see her within months sacked from policing after a 36-year career.

Williams’ lawyers have asked for the case to be expedited and are arguing that the conviction under anti-paedophile laws is unsafe. The first stage is a court of appeal judge deciding whether the case should be heard.

The Old Bailey jury convicted Williams of having the video on her phone. Under the law, she had to show she had a lawful reason to have it in her possession. Williams insisted she never realised the video was there and that it was not clear, from a still from the video shown in her WhatsApp account, what it was about.

She insisted that, despite spending a long time with her sister after the video was sent to her, the video and its contents were never discussed, as the two sisters enjoyed a spa day. The jury convicted Williams of the charge by majority verdict.

But the jury unanimously acquitted her of failing for corrupt reasons to report the video, with the prosecution claiming she failed to do so because she feared her sister would get in trouble. Seemingly, they accepted that she was unaware of the video.

Some of Williams’ supporters saw these verdicts as perverse, and some others as worrying.

The appeal by Williams will say the conviction is unsafe because the jury appears to have dismissed key evidence. This includes two people who also received the video who said they could not tell, from the still in WhatsApp, what its content was.

They also appear, lawyers will argue, to have dismissed an expert who said there was no evidence that Williams ever played the video. The appeal also claims that a recording of a phone call between Williams and her sister, after the sister was arrested, supports the senior police officer’s claim her sister never mentioned the video to her when they spent time together.

Williams was sentenced to community service and placed on the sex offender register despite the prosecution accepting she had no sexual interest in children. She has already started her community service working in a charity shop.

Williams, one of the most senior female African-Caribbean officers in Britain, was praised for her work after the Grenfell fire disaster. She was a founder member of the National Black Police Association, helped to set up a gay police association, campaigned for more women in policing, and had received the Queen’s Police Medal.

Her sister, Jennifer Hodge, 56, was convicted of distributing an indecent image of a child. She sent it via WhatsApp to 17 people, including Williams, who was the only one charged.

Williams has returned to work and is on restricted duties.