I'm not planning to go at the moment but will share what I've Googled...
I also got to Hammersmith tube station.
I'm assuming the
'Go green again means the park (Ravenscourt) almost opposite and then
find the bright red.... This lead me after some Googling to a garden centre you get through to by
going down a tunnel which has painted walls (
decorative and probably lit) and in the picture looks like its painted red on the top half!
Try 'Googling' Ginko garden centre, its on the all london web page, and see what you think!
ps can someone send me a pm to tell how to get an avatar on my profile. Ta very much.