Theatre director Sally Greene described the deal as 'the best deal of my life' in British Airways Business Life magazine.
Ms Greene and her property developer husband Robery Bourne bought the run-down theatre for£90,000 in 1986.
She persuaded the council to guarantee loan repayments for the restoration.
'This£90,000 theatre will have cost taxpayers in Richmond over£10m by the year 2013. It has already cost£2.5m.'
The news comes weeks after Richmond LBC pledged another£150,000 to the theatre, which has operated at a loss for the last ten years, as part of its takeover by the Ambassador Theatre Group.
Sally Greene declined to comment.