To some, they are guardian angels.

Dressed in fluorescent yellow, they play a vital role making sure our children get to and from school safely.

But lollipop men and women are increasingly becoming an endangered species.

Every authority in the country bar one has a shortage of them, a study has found, and in some areas more than half of posts are currently unfilled.

The report by petrol service station Jet found Telford and Wrekin to have among the biggest difficulties recruiting school crossing patrols in the UK.

Nearly 30 per cent of posts in the area are empty, compared to a national average of 17.5 per cent.

The reason for the shortage? According to a poll of school patrol workers, increased traffic and rising instances of road rage are putting people off the job.

As the pace of life gets ever more hectic, two thirds of lollipop patrols claim to have been abused by impatient drivers.

Roy Roley, community campaign manager for Jet, said: "We were really surprised and disappointed to find out that so many lollipop men and women have been verbally abused by drivers.

"They play a vital role in keeping our children safe on the roads and we would urge all drivers to play their part by being courteous and patient at school crossing sites."

Jet, which has been running road safety campaigns for the last five years, first identified the shortage of lollipop patrols in 2002.

The latest research identifies danger hotspots across the country.

Worst nationally was the London borough of Merton where 57 per cent of its sites are not patrolled, 24 per cent up on 2004.

Nottingham had the next worst problem with 52 per cent of positions vacant - a 14 per cent rise.

After Telford and Wrekin, Coventry had the second most vacancies in the West Midlands with 26 per cent of posts empty, a six per cent increase on the previous year.

It was followed closely by Solihull where a 22 per cent shortage was up eight per cent on last year.

Birmingham, Britain's biggest authority, has a 15 per cent shortfall, meaning 69 of its 435 sites remain empty.

Warwickshire managed to slightly reduce its vacancies this year from eight per cent to 6.6 per cent while Staffordshire managed to reduce a 13 per cent shortage to 6.4 per cent.

Figures were not available for the remaining regional authorities.

Solihull Council said the report showed there were some parts of the country in "desperate" need of more school crossing patrols

Councillor Susan Gomm, Cabinet Member for Transport and Highways, said: "We advertise our positions, and have conducted several publicity drives, including one with The Birmingham Post, but unfortunately, although everyone wants a school crossing patrol outside their school, we don't have enough people wanting to be one."

Michelle Wilby, from the authority's school crossing patrol department, added: "In the present climate of increased traffic congestion, we need school crossing patrols more than ever."

As well as traffic and abuse, lollipop patrols cite poor pay and conditions as a deterrent.

Meanwhile in 2004 3,905 children under 15 were killed or seriously injured on Britain's roads in 2004. Of these, 2,339 were pedestrians.