My apologies George for being somewhat late to the 74a party! I've been off at a dental conference and just back in this morning.
Antonin has posted a handsome pink example but since you asked George here is the pink model I acquired from Connecticut based vintage MATCHBOX collector Warren Burdick. What are the odds of Warren finding a spare pink model to sell to a friend? I'm glad he did!
And then here is the white, cream, pink trinity:
This base variation photo (L to R: dark blue, mid blue, sea green, light blue and pale blue) depicts the bases as they were known in the Stannard guide where both the pale blue and so called mid-blue were only known to have the rounded rivet base. Heck, George's photo is better, just go back and look at his.
As I engaged in my original base color variation hunts it was that mid-blue (I believe Christian calls this 'bright blue' and I almost think that is a better descriptor) that came to me last. I would watch on ebay and at shows for darker blue bases with that rounded rivet. I would assume that if a model had the rounded rivet and base darker than the common light blue it had to be what Stannard was calling 'mid-blue'. The first three times I found one I would get the model home and set it beside my 'dark blue' model with the spread rivet base and found that these rounded rivet models all matched the 'dark blue' model I had. It wasn't until my fourth try that I finally got a model with that true mid/bright blue base.
Thankfully Nick has properly noted that dark blue based models can have either a spread or rounded rivet.
Here is a photo showing the square-foot/spread rivet dark blue based model (Nick's code 16) in the center with the round rivet mid/bright blue based model (Nick's code 20) above and the round rivet dark blue based model (Nick's code 17) below. It was the top one that I had a devil of a time finding. It appears in Antonin's base photo that he also has the round rivet base in both mid/bright blue and dark blue:
