Apparently it is a mix of Harimau (Meningkabau? Berantai?) and Cimande styles. As propogated by Cass Magda. www.jkdlondon.co.uk is the website for Impact Martial Arts (UK)-will also link you to the Magda academy in the States.
I do train under Sifu Dave Carnell at the Impact Martial Arts Academy in Stoke-on-Trent. The reason I ask is because there doesn't seem to be that much information around on it. I don't know that much about Silat anyway, but more background would be beneficial. In the meantime, I'll ask my Sifu about it!