The group, which operates 20 sites across the two brands, says it has already told its workforce they would all be made redundant.
Simon Bonney and Micheal Kiely of Quantuma LLP are expected to be appointed as joint administrators.
The business had trialled four trial store openings during June, but these were subsequently closed again last week.
"This a hugely sad day for this wonderful business and its fantastic team; I simply could not ask any more of any of them," says managing director Neil Sebba.
"The risks around COVID19 continues to mean our guests remain at home, and walk-in sales were running at 5% of normal during the trials.
"It is impossible to forecast when Londoners will feel safe to travel on public transport and return to their offices as a result.
“Faced with contributions to furlough starting in August, redundancies became unavoidable.
"Unfortunately, we simply do not have a market in which to operate at the moment, and without a viable solution which had the support of all our creditor groups, the directors regrettably considered that an administration was unavoidable.”