Transport for London’s “Together for London” poster campaign has been ambushed by pranksters who have manipulated the official cartoons to show new messages.

The advertising campaign, which features rounded cartoon characters promising, among other things, not to play loud music or eat smelly food, graces London’s tubes and buses.

The real adverts appeal to people to respect their fellow commuters, with the slogan: “What will you do? A little thought from each of us. A big difference for everyone”.

While it is not the first time the “little thoughts” have been manipulated, a fresh batch of post-coalition slogans has begun to appear across the capital.

These spoof characters (pictured) were spotted on the Number 73 bus route and had been pasted into the bus’s advertising slot so professionally it was thought they could be the latest official posters. They read: “I won’t confront the state”, “And I won’t dissent”.

The guerrilla campaign comes in spite of the well-positioned CCTV cameras that are fitted in all London buses.

A spokesman for TfL said: “We are aware of some instances of offensive stickers being placed on posters on a few of London’s Buses. The posters will be removed as soon as they are reported and TfL is investigating.”

The original campaign was launched by then-London mayor Ken Livingstone in 2008, alongside a mini-film created by Leaving Las Vegas director Mike Figgis.

The three-minute film was screened in around 800 London cinemas, while the poster campaign was developed by M&C Saatchi.

The advertising group is also responsible for the TFL ‘tube or false’ campaign currently featured on tube lines that asks historical questions about the London underground.

The questions include: “One night during WWII 177,500 Londoners slept in tube stations – true or false?”.

It is true; during the war the London Underground installed 22,000 bunk beds, washroom facilities and ran trains that supplied seven tonnes of food and 2,400 gallons of tea and cocoa every night.

According to TFL’s website there were even special stations with libraries, evening classes, films and musical events.