Mandeep Dhami’s first picking season began three weeks ago.

Although the work is physically demanding, the 27-year-old tells me his experience has been an enjoyable one so far.

But some agricultural workers are not so lucky.

Just seven years ago, 23 Chinese cockle pickers drowned when they became trapped by rising tides in Morecambe Bay, Lancashire.

Their deaths exposed the illegal practices of some gangmasters who exploit vulnerable migrant workers.

It also led to the Gangmasters Licensing Act 2004 and the formation of the Gangmasters Licensing Authority, the independent authority that regulates all aspects of the business I was invited to join the GLA on an education exercise near Pershore by director of strategy Darryl Dixon.

The enforcement officers I met at the rendezvous point carried with them leaflets just larger than a credit card.

Printed in 18 languages, these booklets inform the workers of their rights and who to contact for guidance or advice.

Just as we get the call to move on, the officers – somewhat unnervingly – don stab-proof vests. I’m assured these are merely a precaution as the workers will inevitably be using knives. Nevertheless, I’m told not to leave the protection of our vehicle until I’m given the nod.

We arrive at our destination just before 8.30am. There are more than 50 workers in the field, busily hand-picking and sorting spring onions in three groups.

Near me, two men pull the onions from the red earth while a woman deftly trims and tidies the white bulbs and green stems, binding the vegetables into bundles with blue rubber bands.

The workers greet us with smiles and obligingly pose for pictures on this sunny but breezy day.

With panoramic views of rolling Worcestershire countryside and good weather, who wouldn’t be happy working outside?

Mr Dhami is a driver for a group of Indian workers who travel from the Birmingham area five days a week.

Although surprised by the arrival of the GLA officers, together with staff from the UK Border Agency, the father-of-one said it was reassuring.

“It’s quite good they’re looking after the workers and making sure nobody’s being mistreated,” he said.

The GLA officers ask the workers questions based on the authority’s guidelines.

They confirm the agencies employing the groups – known as the labour providers – and the companies growing the produce – the labour users.

In addition to Mr Dhami’s group, there are Romanian, Afghan, Lithuanian, Latvian and Mongolian nationals working in the field.

Staff from the UK Border Agency use a fingerprint scanner to check their identities and entitlement to work in the UK.

Stefin Preda, who moved to the UK from Romania with his family in 2000, has been working as a picker for the past three years.

“I used to have a car wash but I sold it,” said the 27-year-old, who was in the field with his parents and four siblings.

“We start at 7.30am, depending on the weather and work two, three or four days a week. We enjoy it because we make money.”

Amiruldin Hosseni fled the Taliban regime in Afghanistan in 2000.

Since living in the UK, the father-of-three has worked in security but left the occupation to take up picking. The 37-year-old said: “It’s good work. It’s good to look after your staff. Before I came to the UK I was a driver, but there were too many problems. In the Taliban times a journey the equivalent of driving from Pershore to Evesham would take 24 hours because people were always stopping you and asking for money.”

Geoff Tomkins, an enforcement officer for the GLA, said it was important to make workers aware of their rights to ensure they were not exploited.

He said: “We check the agencies supplying the labour are doing the right things. We have a new agency here today and there are a few issues we will now follow up.

“We can follow up with the agencies to check they are complying and if they are not doing what they said, we would take issue.

“That doesn’t mean necessarily revoking their licence. It could mean applying an additional licence condition, for example, if the workers are not being provided with pay slips. They then have to provide evidence they’re doing that.

“The other aspect is to find out if anyone is operating without a licence. You often do find that but most of the farmers know the legislation now and they know people being brought in need a licence.”