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abstract: 'We combine *Gaia* data release 1 astrometry with Sloan Digital Sky Survey (SDSS) images taken some $\sim 10-15$ years earlier, to measure proper motions of stars in the halo of our Galaxy. The SDSS-*Gaia* proper motions have typical statistical errors of 2 mas/yr down to $r \sim 20$ mag, and are robust to variations with magnitude and colour. Armed with this exquisite set of halo proper motions, we identify RR Lyrae, blue horizontal branch (BHB), and K giant stars in the halo, and measure their net rotation with respect to the Galactic disc. We find evidence for a gently rotating prograde signal ($\langle V_\phi \rangle \sim 5-25$ km s$^{-1}$) in the halo stars, which shows little variation with Galactocentric radius out to 50 kpc. The average rotation signal for the three populations is $\langle V_\phi \rangle = 14 \pm 2 \pm 10$ (syst.) km s$^{-1}$. There is also tentative evidence for a kinematic correlation with metallicity, whereby the metal richer BHB and K giant stars have slightly stronger prograde rotation than the metal poorer stars. Using the Auriga simulation suite we find that the *old* (T $>10$ Gyr) stars in the simulated halos exhibit mild prograde rotation, with 