I just found it over at B&C:
http://www.bolterandchainsword.com/topic/266757-high-marshal-land-raider/
He posted the pictures in November 2012, and that was something like 8 months after the "new"
GW paint range came out, so there is a good chance he painted it with the "old"
GW range. If I had to guess, it was painted with Burnished Gold/Auric Armor Gold (or their Vallejo equivalent) and then numerous washes (probably purple, brown, sepia) to give it some depth.