Could employees work for another employer when on furlough?

Yes, provided that it was allowed by the employment contract or the employee agreed to waive the relevant clause. The employee needed to be able to return to work if the original employer recalled them.

Could employees undertake training while furloughed?

Yes. A furloughed employee was able to do training provided that that did not involve providing services to, or generating revenue for, the employer.

Could employees undertake volunteering whilst on furlough leave?

Yes, although employees could not volunteer for their usual employer.