  Nova V458 Vul erupted on 2007 August 8th and reached a visual magnitude of
8.1 a few days later. H$\alpha$ images obtained six weeks before the outburst
as part of the IPHAS galactic plane survey reveal an 18th magnitude progenitor
surrounded by an extended nebula. Subsequent images and spectroscopy of the
nebula reveal an inner nebular knot increasing rapidly in brightness due to
flash ionization by the nova event. We derive a distance of 13 kpc based on
light travel time considerations, which is supported by two other distance
estimation methods. The nebula has an ionized mass of 0.2 M$_{\odot}$ and a low
expansion velocity: this rules it out as ejecta from a previous nova eruption,
and is consistent with it being a ~14,000 year old planetary nebula, probably
the product of a prior common envelope (CE) phase of evolution of the binary
system. The large derived distance means that the mass of the erupting WD
component of the binary is high. We identify two possible evolutionary
scenarios, in at least one of which the system is massive enough to produce a
Type Ia supernova on merging.
