The Henley-in-Arden based business was started in 1909 by Jack Johnson as J.G. Johnson, carrier, serving Stratford, Birmingham, Warwick, and Leamington.

Jack died in the late 1920s, but the business carried on under his wife Blanche and son Phil, who continued running the firm until 1969, with Blanche carrying on into her 90s.

Responsibility then fell to Phil's brother Roy, who was a teacher by trade, and his wife Joan. She remembers the power exercised by 'Grandma' Johnson.

Mrs Johnson said: "Grandma, who had started the business with her husband Jack, was still alive and still very much controlling the purse strings!

"She even still handed out the wages to my husband Roy and his brother Phil, even though they were in their 50s."

The following decade was tough. With four coaches, a removal lorry and a taxi, the firm was always short of drivers so Mrs Johnson took a PSV licence and became one of the first female coach drivers in the country.

She said: "It really was all hands to the pump.

"It was hard work with long hours and each day was a challenge to survive. All of our five children were into their teens, so we had to juggle with the demands of bringing up a family too."

Today two of their sons, John, 49, and Peter, 52, run the firm, which they took on in 1987.

But despite this, John said there was no talk of him joining the firm when they were growing up. He had qualified as a vehicle technician before it was suggested the firm needed someone with his skills.

He said: "We grew up around the buses. The kitchen was where the drivers came in and had their toast and the parking area was our football ground and tennis court when it was empty during the day."

Their father Roy died in 1995 aged 82 but his wife Joan, now 72, is still actively involved in the business.

With 100 years in the same family, Mr Johnson said it was a "privilege" to have got so far. He said: "We look at it now and we are proud of what we have achieved. But I still feel we have a lot to do.

"Peter and I hope we will get the next generation interested."

Mrs Johnson added: "We couldn't have done it without the support of great staff, helpful suppliers, and most importantly, loyal and supportive customers from all over Warwickshire and the West Midlands."

Johnsons Coaches has planned several charity events to mark its anniversary year including charity dinners, an open day and firework display.