It was my job to yellowstone the top step every Saturday after a vigorous scrubbing with hot soapy water. The yellow had to be smoothed on completely evenly, no streak or woe betide me 
The Betterware men were often ex-soldiers and Mum would buy something very small from them. They lugged great, heavy cases of stuff from door to door, poor things.
I can remember all the callers OP spoke about and the Pot Man whose cart had plates, cups, jugs etc. The sides of the van were rounded and slid up (like an old fashioned roller desk) and one side held pots, the other household linens: dusters, tablecloths, tea towels etc.
The Pop Man had those earthenware flagons of ginger beer and dandelion & burdock, but the Sarsaparilla and American cream soda came in glass bottles.
The man who delivered our milk had a horse and cart and dipped a very long-handled ladle into churns to decant into the jug I held. I was allowed to give an apple to his horse.
Eddie Egg, as his name suggests brought fresh eggs from his farm and vegetables in season and occasionally bunches of flowers.
The Spanish onion man was, as others have said, a Breton but Mum sent me out to buy because he always smelled so strongly of garlic. He told me eating raw garlic had kept him healthy.
A Romany lady once told my mother I'd go far - I did, to New Zealand.