Steve, a few points.
The Hoover Junior 1334 was launched in 1958 and mostly resembles the rest of the junior range. The 375, 119 and 1224 are the only Junior's that look radically different to the rest.
The problem with the Turbopower 2 and 1000 is that they were very top heavy. A contact in my local vac shop was recalling how, back in the day, a little old lady had gone out and bought one from some big chain shop but found it too difficult to push - she exchanged it in his shop for a Panasonic.
Argos did stock both the X1.1 and several of the K series cleaners a few years ago, but they only lasted 2 catalogues as they weren't big sellers. The problem with Argos is that people buy things based on the facts infront of them. A 7.5kg, 1150w, £200 bagged upright is never going to out sell a 6kg, 2100w bagless upright at £79.99 - your average consumer would think "this one is more powerful, cheaper and bagless - duh, no brainer!". It's stores like John Lewis, Euronics and independent retailers where Sebo find their customers, because a. the staff tend to know what they're talking about and b. the customer can test drive the machine in-store and see the performance for themselves. If Argos did a full display listing all the features of the Sebo and what makes it so good, drawing particular attention to the lower wattage motor, S class filtration (I think those would be big selling points in todays market) and the reliability record, they'd be much more successful. However, Argos simply stuck them on the page next to all the other bagged uprights