Rainy, I think that the scheme q is(was) in ran along the lines of "x% of group profit will be split amongst all group employees"
If a profit is made, the bonus would be payable, so it wouldn't be discretionary.
If the original contract of employment (and published HR policy) stated that the profit *may* be split, then it could be discretionary, but from the info above it sounds like the bonus is payable.
Of course, there could be complications if the bonus is payable to employees on a given date - if q isn't an employee on that date, there may be a bonus, but not for q.
What has happened to other employees who simply left during the bonus year ? Did they get their part bonus, or was that forgone because they left the job rather than the job leaving them ?
z