That should work to.
http://www.ukba.homeoffice.gov.uk/visas-immigration/transitthroughtheuk/visa-to-transit-landside/
'Transit without visa' concession
If you are a visa national or recognised as stateless, you may be able to transit the UK landside without a visa. To qualify for this exemption:
you must arrive and depart by air;
your onward flight must be confirmed, and must depart within 24 hours; and
you have proper documentation for your destination, including a visa if necessary
Additionally, if you are a national of country covered by the DATV system, you (or a person with whom you arrive in the UK) must hold:
1) a valid entry visa for Australia, Canada, 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.