Models from Gerry Anderson's The Investigator up for sale

Thunderbirds creator Gerry Anderson had high hopes for The Investigator

Two models from a "doomed" TV show from Thunderbirds creator Gerry Anderson are to be sold at auction.

The speedboat and sports car were produced for the 1973 show The Investigator, which never made it beyond a pilot episode.

The models, both fitted with Honda 50cc engines, are expected to fetch up to £8,000 each at auction on 10 October.

Mr Anderson's son, Jamie, said The Investigator had been "doomed to fail from the start".

The Investigator did not make it beyond a 1973 pilot

The car is fitted with a radio-controlled Honda 50cc engine

The show, which charted the adventures of two teenagers shrunk to a third of their size, was abandoned as the concept was considered "too far-fetched" and the radio controlled models were prone to radio interference.

It was seen as a rare failure for Anderson, who also created shows such as Stingray and Terrahawks which used "supermarionation" - a sophisticated form of puppetry. He died in 2012, aged 83.

Jamie Anderson, the managing director of Anderson Entertainment, said after 18 successful series, to have one misfire was "not too bad".

"In many ways it was doomed to fail from the start," he said. "It was a combination of puppetry and live action, but it lacked the science fiction context that made previous shows so successful."

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The models being sold at auction at Sworders Auctioneers are one-sixth scale working models, measuring 221cm (87in) in length. They were designed by Reg Hill and made by Space Models of Feltham especially for the pilot.

Jack Knoll, marketing manager at Security Hazard, a blog dedicated to Anderson's work, said toy manufacturer Dinky was ready to produce merchandise for The Investigator but that Anderson was "too embarrassed" to show the completed pilot to prospective buyer, NBC.

"Budgetary restrictions, and the limitations of using the sophisticated marionettes on location also played a big part in the downfall of the project," he said.

The amphibious speedboat was made especially for the pilot of The Investigator

Auctioneer John Black described the models as "very rare pieces of film memorabilia".

"They pushed a lot of money at these, with remote controlled engines, but it is sad that the series never went beyond the pilot," he said.

The boat and car are being offered for sale by the House on the Hill toy museum in Stansted Mountfitchet, which is making room for new exhibits.