It is a bizarre war that has raged on for years - on one side a serial prankster and on the other the nation's highway authority.

Eastern Daily Press: Another sign for the Thetford Ranges without any graffiti. Photo: GoogleAnother sign for the Thetford Ranges without any graffiti. Photo: Google (Image: Archant)

Anybody travelling into the county via the A11 will likely have spotted the road sign pointing out the Ministry of Defence's rifle range in Thetford, the 'Thetford Ranges'.

And those who noticed the sign may also have picked up on the fact that, often, mystery pranksters have added the letter 'o' to the sign, leaving it instead reading 'Thetford Oranges'.

Now, a Freedom of Information Request has revealed that in the past two years, Highways England - the authority responsible for maintaining the sign - has been called to change it back on three different occasions. The most recent time was in the past few weeks.

With the authority changing its contractor in 2017, details of the number of occasions was only available from April 1 of that year.

But it appears the saga has rumbled on for years.

Janet Adkins, senior business co-ordinator for Highways England, said: "We hold no records of the period of time that the 'Thetford Ranges' sign has suffered changes.

"However, long-serving colleagues have suggested it has occurred sporadically for several years."

While it is unclear just how long the battle has continued, social media posts relating to it date back as far as October 2015.

Mrs Adkins said generally the changes are not reported to Highways England by members of the public, but that they tend to be picked up on by members of the team during route inspections.

They are then changed back as part of a general maintenance work, which includes general repairs, graffiti removal, road sweeping, grass cutting and pothole repairs.

Mrs Adkins added: "As it is not a safety issue it would just tend to be dealt with routinely, rather than as a major priority - generally it just tends to make people smile and they drive on."