Global Williams buys partner out for pounds 45m.
The group bought the 50 per cent of the venture it does not already own from
Far Eastern conglomerate Jardine Pacific which said it wanted to concentrate on fewer businesses.
Chubb China's main operations are in Hong Kong, Macau, Taiwan and mainland China and encompass designing, installing and monitoring fire and burglar alarm systems.
It has the largest central fire and burglar alarm monitoring station in Hong Kong with over 13,500 subscribers.
Williams chief executive Mr Roger Carr said the purchase would allow Williams to integrate Chubb China with its latest Hong Kong acquisition, Guardforce Group, which is also head-quartered in Hong Kong.
Combined, the two have a dominant position in providing security services in the former colony and have significant operations throughout Asia.
Mr Carr said the two together 'represent a powerful hub from which to build future growth in the recovering regional economies.'
The deal was 'another significant step in positioning Chubb as the pre-eminent global security systems and services provider.'
The deal also tidies up Williams's worldwide Chubb security division in preparation for a separate listing as a service company.
It is selling its Yale lock-making division, including its factory in Willenhall, to Swedish group Assa Abloy for pounds 825 million and retaining Kidde as a separate pure manufacturing company making fire extinguishers and alarms.
Chubb China made a profit of pounds 9.3 million last year on turnover of pounds 55 million.
Mr Percy Weatherall, managing director of Jardine Matheson, the Jardine subsidiary which held the Chubb stake said: 'Our strategy for Jardine Pacific has been to concentrate on fewer businesses with good growth potential where we have a significant management role.
'We have had a long and successful involvement with Chubb China, and the sale price reflects the considerable value that has been created.'
Williams shares continued a recovery helped by news of the restructuring plans last month, and edged up 61/1p to 369p.
They have risen from a December low of 283p but are still below the 416p they reached last summer when the group revealed it was in talks to be taken over by US giant Tyco International.