The border between Norwich and Thorpe St Andrew has always seemed rather blurred.

But it is now even harder to establish, following the mysterious disappearance of one of the city's renowned 'Welcome to Norwich' signs from the spot where the two settlements merge.

Council officers are unsure where the board - which usually welcomes visitors to 'A Fine City' - has gone or when it vanished.

A look at Google Maps Street View reveals the sign - which once stood where Yarmouth Road turns into Thorpe Road, near the Harvey Lane junction - has been missing since at least April last year.

But while the main white, red and black sign, featuring an image of the city's cathedral, has disappeared, the additional plates beneath where it was remain in place.

These proclaim that Norwich is a UNESCO World City of Literature and that it is twinned with the cities of Rouen, Koblenz, Novi Sad and El Viejo.

A spokeswoman for Norwich City Council said officials did not know what had happened to the sign. But she said they were "aware" that it needed to be replaced.

However, when that will happen is unclear. She said the council does not currently have a timescale for when a replacement sign would be installed.

In 2011, Norwich City Council agreed to spend £15,000 to replace all the 'Welcome to Norwich - A Fine City' signs, which dated back to the 1960s.

Some had become covered in grime, the ones in Newmarket Road and Sprowston Road had holes in them and the one near County Hall had, like the one on the edge of Thorpe St Andrew, gone missing.

Eastern Daily Press: One of the original signs, in a sorry state, before it was replaced.One of the original signs, in a sorry state, before it was replaced. (Image: Archant)

But it took until 2013 - more than two years after the money was set aside - for the signs to be replaced.

Eastern Daily Press: Flashback to 2013. when Brenda Arthur, then leader of Norwich City Council, revealed the new welcome to Norwich signs.Flashback to 2013. when Brenda Arthur, then leader of Norwich City Council, revealed the new welcome to Norwich signs. (Image: Archant)

The much-loved strapline of 'A Fine City', from a phrase coined by local 19th century writer George Borrow, was retained on the new-style signs, with the UNESCO World City of Literature panels added.

The other Welcome to Norwich signs, which remain in place, can be found at Newmarket Road, Sprowston Road, Ipswich Road, Aylsham Road, Dereham Road, Drayton Road, Earlham Road and Trowse, at the Barrett Road/southern bypass junction.