Speaking outside the Scottish Land Court in Edinburgh where the inquiry is taking place, Mack said the firm would try its best to hit the deadline. But he added: "I'm not Paul Daniels or Doris Stokes. We are just doing our best. We know how important this is."
Earlier in the inquiry Mack said that he had insisted on a design freeze last April. Building revealed last year that between October 2002 and May 2003 4600 design changes were made. He said: "In April last year I was thumping on the table and asking for a design freeze to take place. The project manager wrote that the design freeze should be imposed but changes took place after that and are still taking place as we sit here."
Mack said that the architects, a joint venture between Spanish firm EMBT and RMJM, had ordered seven large-scale revisions since 1999.
The scheme's budget rose again last week, this time jumping from £401m to £431m.
In April last year I was demanding a design freeze – but changes are still taking place
Project manager Alan Mack
The news comes after Bovis rejected allegations that the construction management tendering process in 1998 was rigged.
John Campbell QC suggested to Bovis' commercial manager Brian McQuade at the inquiry on Monday that Bovis knew it would win the contract in November 1998 – just days after it submitted its tender.