As John has already said, valuations are always dependent on condition, so a few pictures would be needed to provide a realistic estimate. As it appears to be a Straight Grip model with wooden grip plates, it will definitely be pre-war with a Ser No rather than a Batch No. The Straight Grip Mk1 was first introduced in 1924 and was available until replaced by the Slant Grip models in 1935. Approximately 50,000 of these pistols were produced and if the Ser No you quote is correct, it would indeed be a very early example of these iconic pistols.

Hope this helps.

Brian