Ice VI is likely to be a major mantle mineral in the interiors of large icy moons in our solar system, and in large icy extrasolar planets. It is also a common accessory phase in our studies of high-pressure aqueous systems. A precise determination of the equation of state of this material will improve our modelling of icy planetary bodies, and also allow us to use accessory ice VI as a pressure calibrant in our laboratory work. We propose to acquire a neutron powder diffraction data in the range 180 K up to the melting point along a series of rough isobars between 700 and 1900 MPa using the Paris-Edinburgh cell equipped with the variable temperature insert. The use of neutrons will also allow us to address questions relating to the proton ordering and/or polymorphism of ice VI in this hitherto poorly explored region of the ice phase diagram.