When Harshad Kothari joined Metro Design Consultants as financial director, the last thing he expected was for his language skills to help win £650,000 of new business. "I was at an initial client meeting with the Indian bank, Bank of Baroda, and when they discovered I spoke Gujarati, they decided they only wanted to deal with me," he says. "I think they felt they could express themselves better in their own language and that helped build trust. In the last two years, we've designed three of their branches."

While much is made of the need for people to learn new languages, the UK's rich diversity means that a strong linguistic talent already exists. With more than 300 languages spoken in London alone, the potential is there for people such as Kothari – who are fluent in one or more of these languages as well as English – to make a significant contribution to our economy and society.

The problem is, says Teresa Tinsley, spokesperson for Cilt, the National Centre for Languages, that we tend to place less value on non-European languages. "If someone is bilingual in German and English, you think they're clever, but other languages that are just as commonly spoken in the world and have just as rich a culture and heritage often get overlooked or downgraded. If you take Bengali as an example, it's one of the most widely spoken languages in the world and yet it holds a low status in some people's minds."

In our increasingly global marketplace, however, this is changing – not least since Asian countries are becoming important trading partners. "All sorts of languages – including Indian languages, Chinese, Korean, Arabic and Russian – are becoming really important strategically. They're also important when it comes to Third World development. If you want to run, say, a health campaign, being able to speak and understand the local language can help you to get the right messages across."

These languages have a huge part to play within the UK too, with a growing need for interpreters and translators to assist in anything from immigration to the justice system to health. "If a child is sick and the mother doesn't speak English, you need someone to communicate with her to find out what's wrong," says Tinsley, who adds that there is also a growing need for bilingual workers in a range of fields from housing to relationship counselling.

It doesn't stop there, with people in practically every job you can think of reporting that they often call on their mother tongue – whether it's a firefighter helping to explain how to prevent fires within a particular culture or a teacher being able to communicate with a child's non-English speaking parents about their achievements in school. "I speak Punjabi and Hindi and that puts a lot of customers at ease and keeps them coming back," says Trishla Jain, who works in Trinity Hospice's Tooting shop. "Quite simply, they can explain what they want."

Vincent Goodorally, an admiral nurse who works with families affected by dementia for the South West London and St George's Mental Health NHS Trust, says: "I'm from Mauritius, so I speak Creole and French, and although there aren't many people from my country in Kingston, there are times I use my native language to help impart information, guidance or emotional support. Families are so grateful because when it comes to emotions, I think people prefer to express themselves in their native language. Also, a lot of words – especially within the health arena – don't translate well. The word 'dementia', for example, literally translates into Urdu as 'you are mad'."

Schools are waking up to the benefits of tapping into existing linguistic talent among children. Little wonder when you consider that more than one in eight English primary schoolchildren already speak a language other than English before arriving at school, and this number is growing. In West Sussex, 50 students annually are now gaining GCSEs in community languages, while at Newbury Park Primary School all pupils learn some simple phrases of a "language of the month", chosen from one of the 44 languages spoken by pupils.

Schools have recognised research showing that people who already speak one language find it easier to learn other new languages and that they tend to perform better across all subjects. Research also shows that bilingual people are better at multi-tasking because they constantly exercise the part of the brain known as the pre-frontal cortex, which reinforces attention processes. What's more, they tend to have a more positive sense of their identity.

Other educational institutions, such as universities, are also starting to tap into the linguistic talent that already exists. Manchester Metropolitan University has launched a new translation and interpretation social enterprise called University Translate, helping local organisations and businesses to reduce the amount they spend on such services. "We have a very diverse population, many of whom are professional linguists, and when we have work we ring them," says Anish Kurien, programme director. "Because we don't make a lot of profit we can keep our costs down, which means organisations like using us. In some cases, we've managed to get them lucrative contracts as a result of, for instance, translating a tender. Everybody wins."

Zak Hussain, whose mother tongues are Bengali and Sylheti, works for the London agency Praxis interpreting for patients in doctors' surgeries. "I love bridging the gap between the two languages and helping people," he says.

For people who want to tie in their linguistic skills with another job, the oportunities are limiteless. Khoa Nguyen, a Vietnamese student counsellor at Bellerbys College for international students, says: "When a Vietnamese-speaking student is having difficulties, I'm here to help. There are a number of us, each with a different mother tongue."

When Dr Nadeem Usmani, a doctor at Willen Hospice, speaks Urdu with Indian patients and their families, he says you can see a weight lift off their shoulders. "They feel more comfortable talking about their emotions and asking difficult questions in their native language. It can make a difficult time less difficult, and that's rewarding."

'It means I can put my patients at ease'

Optometrist Sonal Rughani uses Gujarati and Hindi in her working life both at RNIB's low vision clinic and in a hospital clinic.

"My parents were originally from India, but grew up in Kenya and later moved to the UK. Although I was born here, I didn't speak any English when I started school because my parents had only taught me Gujarati and Hindi. They knew I'd get taught English at school, so they decided to focus on these other languages at home.

Although I wasn't employed for my language skills, I use them regularly in my working life. It means I am able to explain medical information to patients that they might not otherwise understand. It also means I can chat informally with them to put them at ease in what could be a stressful situation. Both help ensure that people from different communities get their eyes tested and, where necessary, treated correctly. It also helps them feel empowered about their condition.

Using Gujarati and Hindi has proven particularly useful when it comes to work with diabetes. I had one case where a man stopped taking his diabetic medication because he had side effects. He hadn't understood why he had to take the pills in the first place, so he just stopped. Because I spoke his language, I was able to go back to basics with him.

One of the things I'm very keen on is community awareness of eye tests. I've also used my language skills to go out and do talks to the community in temples and community centres to explain that eye tests aren't just about updating your glasses."