  We present results for the production of a Z boson in association with single
top at next-to-leading order (NLO), including the decay of the top quark and
the Z boson. This electroweak process gives rise to the trilepton signature
l+l-l'+- + jets + missing energy. We present results for this signature and
show that the rate is competitive with the contribution of the mixed strong and
electroweak production process, ttZ. As such it should be observable in the
full data sample from LHC running at $\sqrt{s}=8$ TeV. The single top + Z
process is a hitherto unconsidered irreducible background in searches for
flavour changing neutral current decays of the top quark in tt production. For
a selection of cuts used at the LHC involving a b-tag it is the dominant
background. In an appendix we also briefly discuss the impact of NLO
corrections on the related tH process.
