Eyebrows have been raised in Norwich in response to an unusual new form of advertising which can be spotted all over the city's pavements.

Clean Graffiti involves using a plastic stencil and a pressurised hose to wash away dirt in the shape of a logo or message.

The result is an image which looks as though it is made with white paint but is actually nothing more than clean stone peering through the city grime.

In the last week adverts for the Sportspark at the UEA and the National Trust's Big Blickling Treasure Trail have been blasted into pavements.

A spokesperson for Norwich City Council said: 'We haven't heard any complaints at this point about these, and it doesn't appear to be harming the city at the moment, but it is something we will keep an eye on.

'While we don't want to stifle creativity and sustainable practises, there is a balance to be struck between these, and having a city overloaded with advertising.'

But Julian Foster, chairman of the central Norich Citizen's Forum, said 'It's a wonderful idea. When people started getting excited about graffiti we said there is good graffiti and there is bad graffiti, but this is good art and it's even better that it washes off after a while - I'm all for it.'

Mariah Rowe, assistant director of the Sportspark, confirmed that it had commissioned its new logos to be placed in 28 places around Norwich as part of its 10th anniversary rebranding.

'The nice thing about it is the clean graffiti aspect. You're actually cleaning something away and it just fades away,' she said. 'It will just bring the logo into peoples' minds.'

'After 10 years we felt the logo still looked good but could look better. Quite a few people have seen it and said it was interesting.'

The National Trust has also commissioned clean graffiti adverts for its Big Blickling Treasure Trail which will take place on September 25 to October 31.

Nick Champion, marketing manager at the National Trust, said: 'The National Trust is about sustainability as much as anything, and so we wanted to use a form of advertising that was sustainable. We decided to use pavement art because we are trying to raise awareness of Blicking Hall within Norwich, because a lot of people think it's quite far away, when really it is only about a 20 minute drive.'

The trust and its PR team organised a teaser advertising campaign, which saw 30 stencils with a small amount of information put around the city two days before the proper campaign, which saw another 30 stencils done with full information about the event.

They were put in prominent locations around Norwich city centre, including Gentleman's Walk, outside The Forum and by Norwich train station.

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