Hi James. The No.4½ looks to be either type 1 (1930-1939), or type 2 (1939-45). If the lateral lever says "WARFINISH" under the surface rust/dirt then it's type 2 - but it looks more like a type 1*. The lever-cap will be nickel plated, not chromed.
*rosewood handles; nickeled frog screws; are...