Letting agency Saxons has been fined more than £3,000 after pleading guilty to the offence of displaying an unauthorised To Let board on a property.
The prosecution was brought by Colchester council after the board was placed on flats; such advertisements require the consent of the local planning authority to be displayed.
The case followed an earlier hearing last April, when the council brought charges against four agencies - including Saxons - for putting up signs without the authority's permission.
At that time William H Brown, Spicerhaart and David Martin group admitted the charges and were each fined £500 plus costs, while Saxons denied the accusations and were summoned to appear for trial at the end of September.
Saxons had been warned by council planning enforcement officers on a number of occasions about their advertisement boards, but the authority says it continued to erect boards without the necessary advertisement consent.
Magistrates fined the company £1,000 and ordered it to pay £2,047.90 in costs.
A council spokesman said the authority would continue to work to stop “the unsightly proliferation of illegal advertising signs” that create “a visual blight on our environment, which affects everyone's quality of life.”