Until 2015, Hollow Water consisted of just Alan Cookson on keyboards and Huw Roberts on guitars. 
They have been producing instrumental material since before 2012. 
This culminated with a loose collection of compositions entitled Jigsaw Music in 2013. 

However. the recently released album Rainbow's End followed a different direction with the temporary addfition of other musicians from diverse backgrounds across Europe and the USA.
Vocals and harmonies were provided by Mark Lock with sax playing from Ilia Skibinsky and Nate Madsen. Additional guitar work was performed my Matt Quistorf. The rhythm section consisted primarily of Jair-Rohm Parker Wells and Stryfer on bass with Siros Vaziri on drums. Steve Giddings pitched in with lap steel guitar work on the title track.
The album has a sci-fi theme involving three acquaintances who form a team and search for a rainbow which stays all the time.

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