Where an employer accepts an employee's application to change from full-time to part-time work must it permit a change back to full-time work if the employee later requests this?

Any change to the terms and conditions of an employee's contract requires the agreement of both the employee and the employer and neither party has the right to impose unilateral changes to the terms of the contract on the other party. An agreement for an employee to move from full-time to part-time work will be a mutually agreed variation to the terms of the employee's contract, which, unless expressly agreed otherwise, will be a permanent change. Any subsequent variation, for example a change back to full-time work, will similarly require agreement by both parties. There is therefore no statutory right for an employee to insist on reverting to full-time work at a future time, although it is of course open to the parties to agree such a change at the time the employee makes the initial request to change hours.