Richards Butler’s potential US beau Proskauer Rose has said Richards Butler needs to raise its profit per equity partner figure of £415,000 to nearer Proskauer’s $1.1m (£580,000) per partner.

Richards Butler and Proskauer entered into merger talks brokered by consultants Blackstone in summer 2004. The talks have now reached the stage where a merger is likely rather than possible.

Proskauer was ranked 58th in The Lawyer Global 100, with gross revenues of £223.4m in 2003. A merger between the two firms would create a transatlantic firm with around 1,000 lawyers and with revenues of more than £300m.

Meanwhile, four partners, who were de-equitised from Richards Butler’s partnership as part of this drive to increase profits, have sought the advice of top employment and partnership boutique Fox Williams. Under the partnership deed, they are entitled to an average of their earnings over the last three years, but Fox Williams head of partnership Tina Williams has been instructed to get them the best deal possible.

The de-equitisation measures are a break from the firm’s culture of caution but were voted through by the 75 per cent of the partnership required for such decisions.

Richards Butler declined to comment. Fox Williams was unavailable for comment.