  If the Solar system had a history of planet migration, the signature of that
migration may be imprinted on the populations of asteroids and comets that were
scattered in the planets' wake. Here, we consider the dynamical and collisional
evolution of inner Solar system asteroids which join the Oort cloud. We compare
the Oort cloud asteroid populations produced by migration scenarios based on
the `Nice' and `Grand Tack' scenarios, as well as a null hypothesis where the
planets have not migrated, to the detection of one such object, C/2014 S3
(PANSTARRS). Our simulations find that the discovery of C/2014 S3 (PANSTARRS)
only has a greater than one percent chance of occurring if the Oort cloud
asteroids evolved on to Oort cloud orbits when the Solar system was not more
than about one million years old, as this early transfer to the Oort cloud is
necessary to keep the amount of collisional evolution low. We argue this only
occurs when a giant (greater than thirty Earth masses) planet orbits at 1 ~ 2
au, and thus our results strongly favour a `Grand Tack'-like migration having
occurred early in the Solar system's history.
