You asked if a national of China needs a visa to pass through the UK in transit.
Yes, you need a Direct Airside Transit (DAT) visa, unless you hold one of the following: a valid visa for entry to Australia, Canada, New Zealand or the United States of America and a valid airline ticket for travel via the United Kingdom as part of a journey from another country or territory to the country in respect of which the visa is held;
a valid visa for entry to Australia, Canada, New Zealand or the United States of America and a valid airline ticket for travel via the United Kingdom as part of a journey from the country in respect of which the visa is held to another country or territory;
a valid airline ticket for travel via the United Kingdom as part of a journey from Australia, Canada, New Zealand or the United States of America to another country or territory, provided that the transit passenger does not seek to transit the United Kingdom on a date more than six months from the date on which he last entered Australia, Canada, New Zealand or the United States of America with a valid visa for entry to that country;
a valid USA I-551 Permanent Resident Card issued on or after 21st April 1998;
a valid Canadian Permanent Resident Card issued on or after 28th June 2002;
a valid common format Category D visa for entry to an EEA State; a valid common format residence permit issued by an EEA State pursuant to Council Regulation (EC) No. 1030/2002; 我们的长居属于这条么？
a diplomatic or service passport issued by the People’s Republic of China; or
a diplomatic or official passport issued by India; or,
a diplomatic or official passport issued by Vietnam.
Transiting to the Republic of Ireland
Passengers must pass through immigration control in order to take a flight to Ireland. Visa nationals (and passengers qualifying for DATV exemption above) may Transit without Visa providing they fulfil the TWOV conditions and are properly documented for entry into Ireland.
DATV nationals transiting to Ireland must obtain a visit visa - not a Visitor in Transit visa which is only for transit to a destination outside the Common Travel Area (Rules HC395 paragraph 47 refers).
All visa nationals wishing to transit the UK but spend longer doing so than the 24 hours permitted under the TWOV concession must obtain a visitor in transit visa for stays up to 48 hours or a visit visa.
Nationals of certain countries, which includes China - unless exempt as detailed above - must have a DAT visa to transit through the United Kingdom. The visa does not allow entry to the UK: other than to catch a connecting flight; leaving from the same airport on the same day; where you do not need to pass through immigration control to catch the flight. This is called Direct Airside Transit.
More information about passing through the UK on your way in transit to another country is available on our Guidance - Transit page.
Any dependants under 16 years old, included on your passport, can be included on the same form, but those older will need to fill in separate forms.
Please make your application to Beijing, Guangzhou, Chonqing, or Shanghai.
Applicants in China should now make their applications through the visa application centres. Visit the embassy's website for more information.
Notes:
A valid U.S. immigrant visa packet (form 155A/155B) is a 'valid visa' for DATV exemption purposes.
An expired I-551 Permanent Resident Card issued on or after 21 April 1998 when accompanied by an I-797 letter issued by the Bureau of Citizenship authorising its extension, exempts the holder from the DATV requirement.
Holding either an I-512 Parole letter or an I-797C (Notice of Action) instead of a valid U.S. visa; or a Transportation Letter instead of a valid U.S. Permanent Residence Card issued on or after 21 April 1998 does NOT qualify for exemption from the DAT visa requirement.
Holding a valid travel document with a U.S. ADIT stamp worded – “Processed for I-551. TEMPORARY EVIDENCE OF LAWFUL ADMISSION FOR PERMANENT RESIDENCE VALID UNTIL…. EMPLOYMENT AUTHORIZED” does NOT qualify for exemption from the DAT visa requirement.
Whether holders of non-national (including refugee travel documents) require a DATV depends on their nationality and whether they qualify for one of the exemptions listed above. So, for instance, the holder of a non-national travel document (e.g. a refugee travel document) who is a national or a citizen of one of the countries listed on the DATV list (e.g. Afghanistan) will require a direct airside transit visa if they are travelling to the UK to transit on to a third country.
楼主 
被拦是在我们祖国大地上，在国内压根就没上去
持有中国护照，你就需要过境签，但是随后我问她有人在英国驻法使馆网站上看到有消息（就是XDJM们广为传阅的visa4UK.doc）说持有长居的过境不换机场是不需要过境签的时候，她也很负责的帮我有询问了别的工作人员，然后给我以下结论：曾经有人因为这个问题咨询过他们，他们也办过这样情况的过境签，因为有些人（没有办理过境签的人）第一次这样走没有问题，第二次走就被查了
（运气问题？）所以他们也不好定论
，问他们是机场哪个环节查的时候，他们说不清楚 =。=
我现在也不知道该不该签了
