That looks like one of those puzzle pictures – “Is one of these things bigger than the other or is it an optical illusion?” Actually, they’re the same size and they’re Conway Stewart 75s. Though it’s not depicted here, there is a slightly shorter 75, and even a bandless one. Judging by the frequency with which it appears in eBay, the 75 may well have been Conway Stewart’s most popular post-war model. It was inexpensive, mostly because the trim was chrome plated instead of gold plated. In 1955, when the 60 cost three pounds and six shillings, and the popular 27 cost one pound six shillings and sixpence, the 75 retailed at a mere seventeen shillings including purchase tax. As the build quality was as good as that of the bigger, more expensive pens and the nib is comparatively large, this made the 75 a good deal back in the nineteen-fifties, and it still is.
This was meant to be a clever side-by-side photo of the two 75 nibs but one was out of focus, blast it, so you only get one! That’s an elegantly-shaped CS 3 nib, if you think of the broad, short 84 nib, or the narrow, somewhat wraparound nib of the 55 for comparison. That’s just about the way a fountain pen nib should look!
If you prefer white-metal trim, as many do, this may be the post-war Conway Stewart for you. After all, these pens were made soundly enough that they have survived intact more than fifty years in their thousands. They come in a rainbow of colours and will likely cost around half what you’d pay for a Conway Stewart 60.