Boris Johnson went to see the custodians at the front door of No.10 to personally apologise for what had happened.
Unions are threatening industrial action over plans to slash civil service jobs by 91,000.
The government efficiency minister said Whitehall had become too bloated due to Brexit and the pandemic.
Minister for "government efficiency" is cracking down on officials working from home.
The prime minister is expected to approve former Vote Leave chair Gisela Stuart's appointment as first civil service commissioner.
No.10 said the civil service had been on the 'frontline' during the pandemic but that it wanted to see workers return to the office.
Education secretary said teachers were among public sector workers set to face "pay restraint".
The health minister's comments have been described as "contemptuous" by unions who say proposed award is a "kick in the teeth".
Philip Rutnam quit as permanent secretary claiming constructive dismissal amid bullying allegations.
The chancellor has frozen pay below inflation for more than a million public sector workers.