The Needle Probe is derived from a "stratospheric reconnaissance craft" of the same name, in an airbrushed illustration by Eric Eden that was first published in the TV21 Summer Extra issue of 1966 and later that year in the Dutch Thunderbirds Extra 2 annual (shown below).* Although I had both the toy and the annual when young, I only noticed this fact when rereading the annual in the 1990s! The same connection has also been independently noticed by editors of GACCH as well as my friends Bill Bulloch and Paul Woods.
The "Defence 2066" spread is part of a 6-page fictitious newspaper feature (TV21 pretending to be a newspaper from 100 years in the future) dealing with vehicles for civil and miltary use as well as various bodies of the World Government. Other than the Needle Probe, the Defence 2066 spread shows the vehicle that became the Nuclear Pulse (qv) as well as the "Battle Chariot" hover tank which almost made it as a toy for the Project Sword series.
For each vehicle, a technical-looking drawing is also shown, together with a brief description and an illustration showing the cockpit. The caption for the colour illustration states that the Needle Probe was "built 2065 for the World Air Force Patrol Force."
*: Thunderbirds Extra 2 annuals are relatively easy to find in Holland (on Marktplaats.nl for example), but before buying a copy it's strongly recommended to check if the Thunderbird 1 paper kit on pp 46-47 is still present. If it's not, you won't have the kit, nor the colour page of the Defence 2066 spread on p 48!