Asking for a friend -
M has been working throughout covid. Attempted wfh in the first few weeks but was impossible from a business perspective so returned to office, all measures in place etc. 2 other colleagues in, rest furloughed due to decline in business,however workload increased for M massively due to others not being in. Holiday booked for August abroad. Employer saying all leave is cancelled indefinitely (despite having furloughed staff that could be swapped in, non critical job, no business reasons). 80% of colleagues been sat at home since April whilst M has not had any time off since Feb.
Can employer force colleague to cancel leave and refuse to unfurlough another colleague to cover them in these circumstances? Don't even start on the quarantine issue - boss has already commented/stipulated that should leave be allowed, M will be a huge risk and must quarantine upon return no matter what the government advice is at the time, which they're trying to use against M.
Any advice please? TIA