I think that G-AXJI is on the Derby Aero club fleet.
“Also, was/is the Pup that much better than a PA28?”
Depends on your criteria;
On the plus side;
The pup is one of the best handling aircraft you could hope to fly
It is semi-aerobatic (I did my AOPA cert in one many years ago)
It looks very nice and the ergonomics are good.
On the down side, compared with a PA28;
Slow for the fuel burn,
Bits are hard to get
It is very over engineered so maintenance is expensive unless you can do the labor yourself.
It cost more to produce than it sold for, so there are not many around.
The doors are a nightmare and tend to come open unexpectedly.
Limited fuel capacity restricts the range (25 gal std)
I had a share in a pup 150 for a number of years and it was fun to fly, but hard work keeping it airworthy.
Rod1