You had to be quick to catch the 23D to the Scrubs

[arrivaarriva]

The route only operated for 18 months in the mid-1930's and AFAIK was the only London D route.  It was a Sunday service using 31 LT's initially, cut back to 26 LT's after six months

[busaholic]

Before the introduction of the 130B express service there was talk of it becoming the 130D instead, but the decision was made that it would only over-complicate a quite complex series of routes!