Richard Pennycuick asked:

>Are there other left hand concertos of interest?

The Korngold Concerto in C-sharp (written in 1923 on commission from
Paul Wittgenstein) is IMO a masterpiece.  Gary Graffman said this
about it:

   To begin with, I find the concerto marvelously pianistic. It
   explores so many possibilities of the instrument - those of
   achieving different types of sonorities - and is wonderfully
   constructed, formally. I find his bittersweet harmonies hauntingly
   expressive. He achieves not just the effect of two hands, but
   sometimes three or four! I agree with Harold Truscott in his
   description of this work as a large symphony for piano and
   orchestra. In fact, I'd go even further and say that the concerto
   is almost operatic.*

   *Quoted in Brendan G. Carroll's "The Last Prodigy," Amadeus
   Press, Portland, Oregon, USA, 1997, p. 166)

Two recordings of the work I have and would recommend are Howard Shelley's
on Chandos CHAN 9508 and Steven de Groote's on cpo 999 046-2.

GeneH