Mick

I'd say it's absent from work without permission - Appropriate punishment would be a Final written warning. Most severe is being dismissed. But the employer has to follow it's own disciplinary policies and procedures and not make rules up as it goes along. Otherwise, the employee could take employer to a tribunal and win on the grounds of unfair dismissal.

It has been known that Employers have had the book thrown at them at tribunals for not following their own policies and procedures.