  We present optical spectroscopy of candidate AGN pinpointed by a Swift
follow-up campaign on unidentified transients in the XMM-Newton Slew Survey,
increasing the completeness of the identifications of AGN in the Survey. Our
Swift follow-up campaign identified 17 XRT-detected candidate AGN, of which
nine were selected for optical follow-up and a further two were confirmed as
AGN elsewhere. Using data obtained at the William Herschel Telescope, Very
Large Telescope and New Technology Telescope, we find AGN features in seven of
the candidates. We classify six as Seyfert types 1.0 to 1.5, with broad-line
region velocities spanning 2000--12000 km s$^{-1}$, and identify one as a
possible Type II AGN, consistent with the lack of a soft band X-ray detection
in the Slew Survey. The Virial black hole mass estimates for the sample lie
between 1$\times$10$^{8}$ M$_{\odot}$ and 3$\times$10$^9$ M$_{\odot}$, with one
source likely emitting close to its Eddington rate, $L_{\rm Bol}/L_{\rm Edd}
\sim 0.9$. We find a wide redshift range of $0.08<z<0.9$ for the nine now
confirmed AGN drawn from the unidentified Slew Survey sample. One source
remaining unclassified shows outbursts rarely seen before in AGN. We conclude
that AGN discovered in this way are consistent with the largely non-varying,
Slew-selected, known AGN population. We also find parallels with XMM-Newton
Bright Serendipitous Survey AGN selected from pointed observations, and
postulate that shallow X-ray surveys select AGN drawn from the same populations
that have been characterised in deeper X-ray selected samples.
