Last updated at 13:13 08 November 2007

Britain's oldest boss is working her usual nine-to-five day at the office - the only difference is she is also celebrating her 100th birthday.

Company director Phyllis Self still drives herself to work six days a week where she manages the bustling garden centre business she has run since 1974.

The great-grandmother works a 48-hour week, dealing with all correspondence, payroll, and the hiring and firing of nearly 200 staff at the Whitehall Garden Centre.

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As she opened her telegram from the Queen, Mrs Self said she has no intention of retiring from the demanding job - and said "keeping busy" was her age-defying secret.

She said: "I've never thought about stopping, retiring or anything like that. I like people too much.

"When people ask how I've got to a 100, I say the secret is just being busy all the time, meeting people and dealing with people. That's what I love.

"I stay at work usually until we close up for the day, and sometimes I'm the last one here, but it keeps me young."

As well as being a director, grandmother-of-five Phyllis is company secretary of the family firm, which has its headquarters in Chippenham, Wiltshire, and a second branch in Bristol.

Her son Chris, 70, is the managing director and two of her grandsons, Peter and Mark, also work for her.

Born Phyllis Johnson in Birkenhead, Lancashire, in 1907, she was the only child to two teachers, who later devoted their lives to caring for orphaned children.

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After finishing school in 1925, ambitious Mrs Self found a job as a personnel officer for a wool mill in Rochdale, where she worked for several years.

She moved to Wiltshire in the early 1930s, to continue her career at Avon Rubber in Melksham, and soon met her husband Roland at a hunt ball.

The happy couple settled at his farm in Lacock where she was a farmer's wife while raising their two children, Chris and John.

Her son John opened the garden centre on a disused field in 1972, but when he emigrated two years later and Roland passed away, Mrs Self and Christopher took over.

She said: "It was only after my husband passed away and John left the garden centre that I thought of working there.

"I was 64 then, and would never have imagined carrying on for this long."

Under their management the business expanded rapidly and the two garden centres are now among the biggest of their kind in the South West.

Thirty-five years later, she still drives her red Mini the short drive to the centre for 9am - and often works a 48-hour week.

She has never taken a driving test because she began driving in the early 1930s before the statutory test was introduced.

Mrs Self, who has 11 great-grandchildren, still enjoys driving to Chippenham and Bath for shopping trips.

"I'm not finding it as easy as I did in my younger days, but I can still do the administration side, although I've had to give up the practical work," she said.

"My son got me a little buggy to go around on, but I don't use it much. I like to walk around the store and talk to everyone.

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"I know all the staff, and have only taken a few days off since we opened 35 years ago.

"I drive to work, but to be honest I've never taken a test. The first car I drove was my late husband's in about 1935."

Mrs Self still finds time to pursue her two hobbies - the local church, St Cyriac's in Lacock, and the Chippenham Floral Society of which she is vice-president.

She professes to have no health secrets, but said: "I have no secrets whatsoever, except that I have never smoked.

"I eat what I like, and like to have a whisky and ginger in the evenings, but that's the only alcohol I have."

The local church held a special communion service for Mrs Self's birthday, and she will be treated to a party for family and friends on Saturday evening.

She said: "I am really looking forward to the party. For some reason, so much has been made of it. It seems other people have got more excited about it than me!

"I don't really see what the fuss is about."