Duke Street Capital has trumped a rival suitor in the battle for dental service provider Oasis Healthcare by offering one of private equity's largest bid premiums in the UK this year, in the latest demonstration of the record wall of money at the disposal of the buyout industry.

Duke Street sealed an off-market deal last night with shareholders Joseph King, ex-deputy chairman at Oasis, Foresight Ventures, Singer & Freidlander, Chelverton and Beringea/ProVen, to secure 27.4% of the company and taking its total stake to 34%, after acceptance from other shareholders and Oasis directors.