NHS, schools and police forces hit by Microsoft outage

Some teachers have reported being unable to access their calendars, emails and files on cloud servers, while parents in several parts of Scotland being told to call to report absences rather than using email.

That has included schools, where teachers, office staff and parents have all had to navigate being unable to access key resources on calendars, emails and internal cloud servers.

One head teacher at a primary school near Newcastle said safeguarding systems had also been affected, meaning staff were having to report concerns in person instead of logging them, while another in Cheshire said his had been forced to delay sending out termly school reports.

Universities have also suffered disruption to online systems, including tools used to submit assignments.

Some, like the University of Portsmouth and University of Aberdeen, have extended deadlines or waived late submission penalties.

The Scottish government has activated its "resilience operations" as it assesses the impact of the outage

Moore added that "good old-fashioned phone lines" seemed to be "the strongest form of communication, especially today".

Caroline Wade, who runs her own PR agency in Kent, told the BBC that the outage had caused "huge disruption" to her work, including one client with an exhibition launch and another running a large public art project in central London.

"You feel that this is something that you can rely upon - it's quite incredible that it's not been sorted yet," she said.

But others were initially glad to hear about the Friday 13th outage - especially as it has occurred just before the weekend.

Martin told the BBC that waking up to no new emails was "absolute bliss" until he realised "today is a crucial day to conclude a business deal".

Meanwhile, one Radio 1 listener described it as "equivalent to an adult snow day".