Pc Kevin Futers stopped and searched three teenagers on the platform of Fleet railway station after they were seen spraying graffiti on an electrical box.

One had a bag containing a "bong" pipe and cannabis resin.

Pc Futers arrested all three for criminal damage and one for being in possession of cannabis.

"All the graffiti was in red spray paint and all had a very specific 'tag' which identifies the artist," said Insp Steve Coward of Fleet police.

"Kev decided to go around Fleet and take pictures of every piece of graffiti he could find. He soon found that the same tag was cropping up time and time again."

Pc Futers went to the house of one of the teenagers, whose parents let him look in his bedroom.

"He found an artist's sketch pad containing graffiti, which he seized," said Insp Coward.

"He then went to the house of another of the lads, searched his bedroom and found more artist's sketch pads.

"His walls were also covered in graffiti.

"Kev compared the photographs he had taken of the graffiti and compared them to the tags in the sketch pads.

"He then arrested the second youth, a 17-year-old from Fleet, who admitted numerous offences.

"The teenager was charged with criminal damage and convicted at Basingstoke Youth Court.

"He also asked for 26 further offences to be taken into account.

"He was ordered to pay court costs of £20 and was given a referral order to a youth offending team for four months."

Insp Coward added: "We worked out that the cost of the repairs would be £40 an hour for treated walls and £60 an hour for untreated walls, using toxic chemicals.

"Overall the cost to the local taxpayer worked out at between £5,000 and £10,000."

Insp Coward was full of praise for Pc Futers.

"The sheer amount of investigation that went into this case really did impress me," he said.

"Kev recognised that this was more than a one-off occurrence and took the time out to go round and take photographs of all the incidents of graffiti in Fleet, which I thought was highly commendable.

"These acts of graffiti do annoy people and it's one of those things that has an annoying habit of spreading."