@Don McErlean , in 1932 on Hornby offered a "revised body Style" of the No.0 locomotives ( colloquially called "Longsplashers", referring to the longer one piece splash guards over the wheels ) and in 1937-9 they also made some without the steam chests , possibly as a cost cutting measure to appeal to more cash strapped buyers ?
UK retailers were a funny bunch and some of the emerging "supermarket" chains would only stock some things like toys if they were "unbranded" , Gamages was one such retailer .. In this way Meccano was able to make some money from these chains without technically undercutting their existing dealerships . Note the description in this post war train ad 
Meccano actually produced a set with no Hornby branding at all under the name " British Express"
