Simon Wren ) gurgled happily, sounding much like they
were saying :

From the TFL website:

Which vehicles would be affected?
A Feasibility Study was undertaken between 2001 and 2003 to assess the
options for introducing a LEZ. The Study found that it was most
effective to target heavier, diesel vehicles and potentially LGVs as
they typically emit more pollution per kilometre driven.. There is no
intention to target cars with the proposed LEZ.
From early 2008, the proposed LEZ would affect Heavy Goods Vehicles
(HGVs) over 7.5 tonnes. From mid 2008, the proposed LEZ would affect
HGVs from 3.5 to 7.5 tonnes, buses and coaches from mid 2008.
The LEZ could potentially be extended to cover diesel-engined Light
Goods Vehicles (LGVs) from 2010 subject to further analysis.
The LEZ would affect all vehicles entering the zone, wherever they are
registered.

http://www.tfl.gov.uk/tfl/low-emission-zone/faqs.asp

How does that relate to participants in the London to Brighton run?

This para relates...
"There is no intention to target cars with the proposed LEZ."