The SP5 was launched with a lot of attention in Airgun World, but as it was a modified Milbro Diana G80, the least sexy of the British makes, it didn't sell well at all. 5mm calibre gave it a choice of about four different pellets so that didn't help much either. Joe Public preferred a Mercury, the non-patriots a HW35 or a Feinwerkbau Sport if they could afford one.
I would be very surprised if they made more than two or three of these special models, and I doubt that Eddie sold more than a few dozen of the standard SP5 model. He might have sold more of the .177 Target version to Cadet forces and so on.
Which is probably a shame as I understand it is quite a good rifle of that era, and the Milbros I have dissected aren't significantly less well made than their BSA or Webley counterparts.