Just before the new puppet satirical show Newzoids (Wednesday, STV, 9pm) started, I looked up a few clips of the old puppet satirical show Spitting Image.

Was it as good as I remembered? I was too young for the cult of The Young Ones, but I was 14 when Spitting Image started in 1984 so its swagger, insolence and unpleasantness felt just right. I was a teenager - I was a bit swaggery, insolent and unpleasant myself.

In the 30 or so years since then, the Spitting Image clip that keeps being reshown is the one with Margaret Thatcher and her "vegetables" or Cabinet ministers. But I enjoyed being reminded of some of its other scabrous highlights: Peter Mandelson as a sibilant snake, Kenneth Baker as a slug, probosci wobbling unpleasantly, and the Queen Mother with the voice of Beryl Reid.

There was also a wonderful sketch in which all the Royals lost their money and were forced to live in a council flat. "Only four rooms between us?" says Prince Philip. "I'll have to sleep in the same room as my wife!" And some of the sketches even seem prescient now: in one, Jimmy Savile is ushered into a cell after viewers ask the authorities to fix it for him to be locked up for good.

When the show finally finished for good in the mid 1990s, it wasn't because the politicians of the day were beyond ridicule (quite the opposite: the leader of the Labour party at the time was Tony Blair), it was because we'd become familiar with the format and it was no longer enough to see famous people formed from foam rubber. The jokes had to be good too, and sometimes they weren't.

In reviving the genre, Newzoids faces the same problem: it can't rely on us being amused solely by the sight of the puppets - the material has to be sharp as well, and some it was and some it wasn't. Ed Miliband facing the ultimate bushtucker trial on I'm a Celebrity - eating a bacon sandwich - was witty; Alex Salmond singing "we hate the English" wasn't.

The puppets on Newzoids were also not nearly as grotesque and misshapen as they should have been. These big faced marionettes with Thunderbird eyes could have fitted into Trumpton or Toy Town and no one would have batted an eyelid - perhaps because they have no eyelids to bat, perhaps because the Newzoid puppets are made by a company that usually does children's shows.

What was definitely innovative about the Newzoids puppets though was the way they mixed old-school marionettes with computer generated imagery, but that wasn't enough to shake the feeling that they were re-using some of the old Spitting Image ideas - in Spitting Image, the Queen Mother was a vulgar commoner, in Newzoids, the writers did the same joke with the Queen, casting her as Mrs Brown.

There was one stand-out success though: the Ed Miliband puppet, possibly because the jerky, wooden format of puppetry is perfect for our country's foremost jerky, wooden politician. But looking back at the old Spitting Image clips reminded me that a politician who's easy to send up isn't necessarily a politician that's easy to write off. Remember the famous grey-faced John Major puppet? Spitting Image used that puppet to mock Major week in, week out in the early 90s, as Newzoids may do with their Ed Miliband. But in the end, Spitting Image didn't matter. That grey-faced man called John Major won an election.