These were the dedicated City magazines annuals that were published during the mid to late sixties.
These two Thunderbird books are a little different. The TV Century 21 book from 1966 wasn't an annual but it did contain strip stories and features in similar vein to an annual rather than just a straight forward story book. The other annual was published by Polytstyle in 1971 as part of their Countdown/TV Action comic spin off books.
The artwork from the inside cover of the 1966 Thunderbirds story book.
The Polystyle 1971 annual featured two brand new Thunderbirds strip story's drawn by Ron Turner.
This 'Thunderbird' annual published by City Magazines in 1971 wasn't what it seemed. It was simply a TV21 annual by another name and a last gasp catering for readers who had enjoyed TV21 prior to it amalgamating with Joe 90 comic.