A GUERILLA marketing campaign in St Albans and Harpenden could backfire after the police were asked to investigate residential letting signs being covered with unpaid-for stealth advertising.

Confused residents and landlords complained to letting agents after discovering that, in a cheeky move, many signs on private property advertising rental housing had been overlaid with black plastic and a picture of a bull.

The signs created a headache for unimpressed local letting agents as they could be seen in prominent positions along residential streets throughout St Albans and Harpenden earlier this week.

Agents had to either pay their signage supplier to remove the advertising or drive along streets to take them off themselves.

While no one has claimed responsibility for the unconventional advertising, an internet search has found website bulllettings.com bearing the same picture of a bull. But it adds further to the mystery by not giving any contact or other details, saying only: “coming soon … no bull, just lettings.”

Further investigation shows there is a company with the same name recently registered to a Harpenden address, but again, there is no contact information to show whether it is the same company.

A spokeswoman for Herts Police confirmed that they have received complaints from agents about the “underhand tactics”.

She said it was a civil matter and details have been forwarded to the Trading Standards Institute for further investigation. No-one there was available for comment before the Herts Advertiser went to press yesterday.

Johanna Attewell, lettings manager at Abbey Estates, said the firm’s signs were among the many targeted by the guerilla marketing.

She said: “We haven’t seen this type of thing before. It’s unusual. It’s obviously advertising a new agent, but it’s a very strange way to promote yourself.

“We are not taking it too seriously, as we don’t see it as a positive way to advertise. But it has created some talk locally among agents.”

Johanna said she had spotted the bull signs on Sunday night, but had no idea what they were advertising.

She said Abbey Estates had tried to find contact details for Bull Lettings to see if they would cover the cost of having the stealth advertising removed, but to no avail.

Johanna added: “It is very annoying.”

Chris Knight, owner of Knight Signs, whose letting signs have been illegally covered, said he had been contacted, “by quite a few agents who have been affected”. He added: “I have to go around and take them down.”

Chris said he did not know exactly how many signs had been covered, but it had occurred in both the city and Harpenden.

He added: “I don’t know what the outcome is going to be. It’s a publicity stunt but it’s a problem because the agents have to pay me to remove it.”

The superimposed signs quickly became the topic of discussion on Twitter with many local businesses unimpressed, such as Heaven is a Cupcake which tweeted: “It’s not the best way to get known. I’d be annoyed.”

The Green Boutique replied that it would result in negative publicity, while Let Me Properties tweeted: “Really disrespectful to all of us.”

St Albans district council’s development management manager Laurence Moore said: “This matter has been brought to our attention and the council’s planning enforcement team are looking into it.”

Under the Town and Country Planning Control of Advertisements (England) Regulations 2007, estate agents are able to place “for sale” and “to let” signs on the land that they are selling or letting, subject to permission of the landowner.