Still no RTR Southern 4-6-0s just two kits BHE N15, and Langley S15, an H15 can be made from either of these using a chassis with scale 6' drivers, a Nelson could be hacked from a Scot or Jubilee. Of the Drummond 4-6-0s only the T14 lasted for any length of time, I remember seeing an occasional one, the last one was scrapped in about 1951.
I often wonder who has my old Nelson, it probably found it's way onto Ebay or on sale at a show, I let someone do a refurb  on it and a few other SR locos in exchange for a load of chassis, bodies and other bits  I know an H15 found it's way onto Ebay so assume others did I never saw any or the requested refurbs returned, including a Nelson and Arthur as well as the H15