Hi,
I am sorry that I do not have any information about the 23/4 you mention, however, I do know of a Douglas Club member wishing to sell a 1924 23/4 SW model.
I do not know him personally other than a Club member but have seen photographs, the bike looks original and in good condition. If the deal with the Dutch guys does not happen and you are interested in a bike from UK please email me direct from the forum and I will put you in touch with him.
Dave