The business is one of five key shareholders in the troubled London Underground maintenance company, which is on the verge of going into administration.
A spokesman for the practice said, 'Our trading figures were good last year and this will not have an impact on the architectural side of the company.'
Yesterday it emerged that Chris Bolt, the statutory arbiter for the London Underground's Public Private Partnership Agreements, had offered the struggling group just £121 million over the next 12 months.
A statement from Bolt, who found that Metronet's costs were at least £243 million higher than previously expected, said: 'The arbiter has - reached the view that if Metronet had delivered in an efficient and economic way, its costs could have been lower.'
Metronet is backed by stakeholders WS Atkins, Balfour Beatty, Bombardier, EDF Energy and Thames Water - all of which may be asked to pump in extra cash to keep the company afloat.