Hi,
It better to obtain visa to avoid any surprise suitation. However, on their website they have clearly given an option as below & at the time of transit officer will access our documentation if he/she found any weak points he will off-load the passenger(s), I know one pakistani friend who resides in riyadh, travel from Riyadh to London and London to Toronto and he won't faced any issues during transit. Rest all of the best!
'Transit without visa' concession - DATV exemptions
If you are a national of a country covered by the DATV system, you may be able to transit the UK airside without a visa. To qualify for this exemption:
You must arrive and depart by air;
Your onward flight must be confirmed,
You must depart within 24 hours;
You have proper documentation for your destination, including a visa if necessary.
Additionally, you must hold:
1)
A valid entry visa for Canada, Australia, New Zealand or the USA, and a valid airline ticket for travel via the UK, as part of a journey to or from one of those countries; or
2) a valid airline ticket for travel via the UK as part of a journey from Australia, Canada, New Zealand or the USA, if you are transiting the UK no more than 6 months after the date when you last entered Australia, Canada, New Zealand or the USA with a valid entry visa for that country; or
3) a valid USA I-551 permanent resident card issued on or after 21 April 1998; or
4) an expired I-551 permanent resident card issued on or after 21 April 1998, accompanied by an I-797 extension letter issued by the Bureau of Citizenship; or
5) a valid Canadian permanent resident card issued on or after 28 June 2002; or
6) a valid Australian or New Zealand residence visa; or
7) a valid uniform format category D visa for entry to a state in the European Economic Area (EEA); or
8) a valid uniform format residence permit issued by an EEA state under Council Regulation (EC) number 1030/2002; or
9) a valid UK residence card; or
10) a valid EEA family permit issued by the UK government; or
11) a diplomatic or service passport issued by the People's Republic of China; or
12) a diplomatic or official passport issued by India; or
13) a diplomatic or official passport issued by Vietnam
van100 said:
For Jordanian passports yes up to 24 hours
Chinese, pakistan etc No