Other than the traffic islands, the London Place section only uses paint. There is no central vehicular barrier (will check).

"""
Roads are not to be mapped as dual carriageways if the two directions are only separated

* by paint. This includes single or multiple painted centre lines[1], hatched areas, channelized turn lanes[2], two-way turn lanes[2],
* by flush medians[3],
* or by any other means that is not a physical barrier to vehicles.
""" -- https://wiki.openstreetmap.org/wiki/Dual_carriageway

There may be a section it's reasonable to map as a short D.C. section to the NE of the Marston Rd traffic lights, but it's quite short. Is it worth it?

It's wide-sh, so an area:highway could be applicable for the micro shape mapping?