  Spin-orbit coupling has proven indispensable in realizing topological
materials and more recently Ising pairing in two-dimensional superconductors.
This pairing mechanism relies on inversion symmetry breaking and sustains
anomalously large in-plane polarizing magnetic fields whose upper limit is
expected to diverge at low temperatures, although experimental demonstration of
this has remained elusive due to the required fields. In this work, the
recently discovered superconductor few-layer stanene, i.e. epitaxially strained
$\alpha$-Sn, is shown to exhibit a new type of Ising pairing between carriers
residing in bands with different orbital indices near the $\Gamma$-point. The
bands are split as a result of spin-orbit locking without the participation of
inversion symmetry breaking. The in-plane upper critical field is strongly
enhanced at ultra-low temperature and reveals the sought for upturn.
