Sick people frequently turn up in the commons for critical votes. Diane Abbot is even taken to task by her own party for failing to vote because of a migraine..
The Guardian:-"Diane Abbott has been accused of cowardice and asked to apologise by a fellow Labour MP after missing the historic article 50 vote on Wednesday evening.

Despite claims from the shadow home secretary's office that she had fallen ill with a sudden migraine, John Mann claimed she "gave herself a sick note" rather than help to trigger Britain's exit from the EU."
    True or false her non vote will likely destroy her career and credibility.