The firm, which employed around 70 staff and also traded as 21 Construction, fielded all calls through to an automated answer service earlier this month, raising the alarm among suppliers.

Other subsidiary companies Twenty 1 Construction and Twenty 1 Interiors were also placed into the hands of administrators from Grant Thornton at the end of last week.

The firm had risen steadily in the London market recently completing fit-out jobs for British Land on the Broadgate tower and for client CIT on the Finsbury Tower.

Twenty 1 Construction was set up just over 10 years ago by fit-out industry veterans Keith Ashcroft and Paul Gaughan.

Ashcroft had previously worked at John Doyle group-owned Ibex Interiors as a construction director for 15 years, while Gaughan had previously worked for Byrne Group-owned fit-out arm Chorus for six years and before that also worked at Ibex.

Twenty 1 Constructiion grew steadily from around £13m turnover in 2015 to around £68m in most recent published accounts for 2020. Around a third of revenue was generated on complex refurbishment jobs and the rest from commercial fit-out work with an expertise in occupied premises projects.

The firm is understood to have been impacted hard by the early pandemic taking out a £2m coronavirus large business interruption loan facility with HSBC in October 2020.

A spokesman for Grant Thornton said: “Following significant disruption, reduction in activity levels and financial pressures experienced due to the Covid-19 pandemic, its directors have elected to place the group into administration.

“Unfortunately, this has meant that works at current project sites have stopped and the majority of employees have been made redundant. In line with their statutory obligations, the administrators’ priority is now to maximise value for all of the company’s stakeholders, including its employees and creditors.