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We present a new spectroscopic study of the dwarf galaxy Bootes I (Boo I)with data from the Anglo-Australian Telescope and its AAOmega spectrographtogether with the Two Degree Field multi-object system. We observed 36high-probability Boo I stars selected using Gaia Early Data Release 3 propermotions and photometric metallicities from the Pristine survey. Out of those,27 are found to be Boo I's stars, resulting in an excellent success rate of 75%at finding new members. Our analysis uses a new pipeline developed to estimateradial velocities and equivalent widths of the calcium triplet lines fromGaussian and Voigt line profile fits. The metallicities of 16 members arederived, including 3 extremely metal-poor stars ([Fe/H] < -3.0), whichtranslates into a success rate of 25% at finding them with the combination ofPristine and Gaia. Using the large spatial extent of our new members that spansup to 4.1 half-light radii and spectroscopy from the literature, we find asystemic velocity gradient of 0.40 +/- 0.10 km/s/arcmin and a small butresolved metallicity gradient of -0.008 +/- 0.003 dex/arcmin. Finally, we showthat Boo I is more elongated than previously thought with an ellipticity ofepsilon = 0.68 +/- 0.15. Its velocity and metallicity gradients as well as itselongation suggest that Boo I may have been affected by tides, a resultsupported by direct dynamical modelling.

The Pristine Dwarf-Galaxy survey -- IV. Probing the outskirts of the dwarf galaxy Bo\"otes I