Hi JPC,
I look after the various publications reproduced by the Douglas Club, we do have some information on the EW.
One book entitled Care and Maintenance of the 350 models 1926-1930, does cover some details of the EW.
I may be able to help with some further information.
All the Club reproductions are sold at a reasonable cost, The initial outlay is financed from Members subscriptions together with the profits from sales. All the profit is used to obtain further information and finance the printing of more manuals and useful publicity material.
Please feel free to email me direct using the email ikon below my picture. I will send you more complete details of what we have that may be of use.
Of course the best way forward is to join the Club, when you will have even more access to thpose with a wide experience of the EW.
I look forward to hearing from you.
Dave