Hi Herman,
Millard Brothers, of London, are variously listed as Hardware Merchants & Factors, skate manufacturers, and tool makers & dealers from, at least, 1895 to 1947. Additionally, I found online information which indicates the firm was established in 1887, by Oliver L. & Samuel E. Millard, at Stockwell Road SW, London (though I don't find them in the 1891 London directory). A 1945 advertisement also includes the wording "Established 1887."
http://www.gracesguide.co.uk/wiki/Image:Im1945Benn-Millard.jpg
The firm continued in business until the 1980's, though their product line switched increasingly to air rifles and other sporting goods after WWII. Based on this, I would list their relevant dates and locations as follows (for now):
Millard Brothers London 1887 - 1947
Stockwell Road SW [1887]
123 Houndsditch E [1895 - 1915]
467 Caledonian Road [1920 - 1935]
467 - 471 Caledonian Road & 76 Great Eastern Street EC 2 [1945]
My impression is that, while they manufactured some items, their primary business was the retailing of a variety of wares from a number of other manufacturers. In which case, while they may have actually manufactured your saw, it is just as likely that another firm made it and stamped the Millard Bros. name on it. The advertisement, linked to above, is consistent with this pattern, I believe.
I've located online auctions of a couple of other Millard Brothers saws, and it doesn't appear that they are particularly collectible. So, if it is in good enough condition to warrant putting back into use, I wouldn't hesitate to do so.
Don McConnell
Eureka Springs, AR