Mosley joined the band in 1984 after a long search for a replacement for Mick Pointer, who had left the band in 1983. He was the fifth drummer to play for Marillion and was frontman Fish's choice for the role, having been unhappy with the band's previous drummers. Mosley had previously, among others, played with former GenesisguitaristSteve Hackett, both on two of his solostudioalbums and on tour. He also played on the 1975 album Birds by Dutch band Trace and on fellow Marillion bandmate Pete Trewavas' and Eric Blackwood's Edison's Children album "In The Last Waking Moments...", playing drums on the epic 16 minute "The Awakening". He is still a member of Marillion to this day.
Personally, I still don’t really know what progressive means. In some people’s minds if a piece of music is over 10 minutes long, it automatically gets the label of being progressive. I always enjoy playing arrangements kind of in a classical format, which is in movements. To me, music is either good or bad; it doesn’t matter what the label is. The kind of progressive label that I don’t like is the one that involves lyrics that quote dancing gnomes, Stonehenge and fairytales, etc.