Baroness Dunn insists her "confidence in Hong Kong's future is unchanged" and that she is moving for personal reasons. Her protestations will be largely brushed aside, along with the memory of assurances that she intended to stay after 1997.
The most recent assurance came after it was disclosed that she and her husband, Michael Thomas, a former Attorney-General in Hong Kong, had purchased a substantial 18th- century country house in Gloucestershire. They also own a luxury flat in Knightsbridge. Her departure is a severe blow to confidence in Hong Kong. The Governor, Chris Patten, issued a low-key statement noting her "enormous contribution to the community", but significantly did not announce a replacement for her in his executive council.
Most of the people most closely identified with the British have scrambled aboard the new Chinese vessel entering Hong Kong harbour. Sir S Y Chung, Baroness Dunn's predecessor on the executive council, is now an official adviser to the Chinese government. Three other executive councillors, a High Court judge and a British ex-acting governor occupy similar positions.
Although the Hong Kong press has speculated that China might find some role for Baroness Dunn in the new order, this always seemed unlikely. She has gone against the trend by reinforcing ties with Britain, principally by accepting appointment to the House of Lords in 1990 and also by maintaining high-profile positions in British companies, including HSBC Holdings, the parent company of the Hongkong Bank.
In recent years she has maintained a low profile in Hong Kong. It is officially denied that she has any policy disagreements with the Governor, although his more aggressive style is in marked contrast to her consensual approach.
Baroness Dunn, 55, has been one of the pillars of the Hong Kong establishment ever since she was taken into the legislature by Sir Murray (now Lord) MacLehose, the powerful governor who ruled in imperial manner for the better part of the 1970s.
During negotiations for Hong Kong's return to Chinese sovereignty, she accompanied Sir S Y Chung at a famous meeting with China's paramount leader Deng Xiaoping, at which they incurred his wrath by insisting they had come as representatives of the Hong Kong people. He rejected the idea that Hong Kong people had an independent role to play in the negotiations.
Like other members of the old establishment, Baroness Dunn was paralysed by shock over the 1989 massacre of pro-democracy protesters in Beijing's Tiananmen Square. Nevertheless, she did lead the effort to formulate a united position among legislators pressing Britain for a more democratic system than that introduced by Mr Patten. Like others, she abandoned it in the face of Chinese opposition.
It is hard to dismiss both her calculated charm and ability to articulate Hong Kong's position to an international audience.
Perhaps Baroness Dunn's decision to abandon Hong Kong was taken long ago when she became one of the few Chinese to anglicise her name. In fact she shares the Deng family name with China's leader.