I can still remember way back when, some lucky kid showing off his example at junior school and have it trundle across the school playground with lights flashing. I'd be extremely surprised if his still exists, as they aren't the most robust of toys.
These days, they are considered the highlight of many a Gerry Anderson vintage toy collection, with some dealers asking eye-watering prices for even slightly damaged ones, even if it hasn't got the all-important SWORD Supremo badge. Thankfully I got mine before prices got silly.
Of course, The SWORD badge is quite a bonus as it helps tie-in the C21 ZX with the SWORD range.
The box which has no real Thunderbird logos except for 'as seen in Thunderbirds Are Go' on one side, but it has a nice publicity photo of Zero X hidden under the flap and on the side.