Windsor reported profits up by 8.6% to £1.17m before tax in the six months to the end of March from £1.08m.
Brokerage and fees increased by 5.5% to £7.5m from £7.1m in the same period the year before.
Earnings per share increased to 1.26p from 0.86p. Windsor paid £4.5m during that period towards the price of the remaining 45% minority share in its subsidiary Windsor Professional Indemnity (WPIL). The final price could be up to £9m.
Group finance director Christopher Murphy said: "PI rates are still increasing and the market is still tight. It is having the same competitive pressures as any other PI broker."
The group's other main division, Windsor Insurance Brokers, is being reorganised by managing director John Bennett.
The group does not disclose contributions of subsidiaries, but its public accounts for the year ended 30 September 2002 show Windsor Insurance Brokers made operating profits of £410,000 on brokerage and fees of £5.5m against profits of £391,000 on £4m the year before.