That's score nice bike frame
It is a Roadmaster, as they made bikes for the Whizzer and Marman motor kits.
The bike and motor kit (Whizzer or Marman) could be bought together and the buyer had to install the motor. Not a factory production Whizzer
The frame you have is not the early very rare 1948 CWC Whizzer frame for the early 48 Whizzer Pacemaker Factory production bike.
Here are some pics of the real deal early 48 CWC Whizzer Pacemaker. I'm sure you will see the differences
Gusset on the frame neck and rounded rear end
Sorry the pics are fuzzy I took em off the net
View attachment 103272View attachment 103273View attachment 103274View attachment 103275View attachment 103276