A retired Norwich teacher has published a quirky booklet about devices he believes were installed to discourage people from urinating in the city's streets.
Ray Loveday, from Pottergate, thinks he has spotted 40 'anti urination devices' (AUDs) in Norwich, which he believes have been added on to buildings to stop men from urinating there.
The 83-year-old, who began recording his findings in 2012, said: 'Because these little brick concrete things in a corner, well what else are they for? You can't stand milk bottles on them or sit on them. What good are they?
'I thought I would do it to stir up a little bit of interest. I thought someone ought to do it and Ray Loveday might be the one to do it, because after all I am a bit cheeky.'
Mr Loveday claims the devices are usually found nearby pubs, around churches and down alleyways.
He said: 'Nobody knows what they are, it's my theory and most people are agreeing with that. That is what they are for. If people don't believe it, I ask them to come up with a reason.'
The 32-page booklet includes historical information about the devices, photos of where they are and an AUD trail map.
Mr Loveday's city centre trail starts at The Guildhall on Gaol Hill and finishes back where it began, taking in 10 AUDS.
He added: 'I think the trail is going to open people's eyes to something that they probably have seen but never knew what it was for.
'But I do know at least one person who has tested them out and the splash back effect does happen.'
In the booklet, Mr Loveday tells of his first encounter with AUDs, which was in Swaffham during the 1940s.
He said: 'My brother drew my attention to little brick or concrete features fitted into some buildings. I was much intrigued when he explained their function.'
The majority of the examples used in his book can be found in Norwich.
Other pictures featured have been collected from Bungay, Diss. Ely, Great Yarmouth, King's Lynn, North Walsham, Swaffham and Thetford.
So far he has failed to find any AUDs in Cromer, Dereham, Fakenham and Sheringham, but he hopes people will carry on the search for them in these towns.
AUDs An Intimate Study of a Minor Architectural Feature, is available at Inanna's Festival and City Bookshop for £3.
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