When Inga Ruby joined Gieves & Hawkes as PA to the chief executive, she found herself so well suited to the firm that she volunteered to catalogue its illustrious history - and there was a lot of it.

Founded in 1771, Gieves & Hawkes has held royal warrants as tailors for 200 years, measuring the inside legs of kings and national heroes.

“It takes up my Saturday mornings at the moment,” she says. “It's a labour of love, working alongside the archivist. The project was started by Robert Gieves, a fifth generation descendant of the original Mr Gieves, but he sadly died before it was complete. We've found some fascinating items, including the original ledger for the Duke of Wellington. When we have finished, there will be an archives room, celebrating our firm's history.”

Inga previously worked for Agent Provocateur, creators of saucy underwear. Was she concerned that joining a traditional men's tailors might be a little stuffy? “It's certainly not fuddyduddy,” she says. “In its own way, men's tailoring is just as exciting as erotic lingerie. However, the dress code for Agent Provocateur was relatively casual - here, I wear high heels and suits. Agent Provocateur was fun. But I decided to move on because I wanted a new challenge. I put my CV online and it was spotted by a recruitment agency.

“I have an extremely varied role, because Mark not only runs Gieves & Hawkes but also chairs the Savile Row Bespoke Association, which he set up with four other companies to protect and promote the art of bespoke tailoring. I provide all the administration for it. I manage Mark's diary, field calls and e-mails, arrange meetings, liaise with our overseas offices, co-ordinate his frequent trips abroad and look after his multicurrency expenses. I also run events and edit the company magazine.

“It's important that Mark always looks the part, so I ensure that his suits are pressed and if I notice he needs a haircut I'll discreetly book him an appointment. Our working relationship is open and positive, and he trusts me to get on with things - important when he's away so much.”

Mark says that Inga was obviously tailor-made for her job: “My first impression was of someone who was alert and interested, and full of humour and character - exactly how she has turned out.” Mark originally planned on being a lawyer; but he packed in his degree and embarked on a career in marketing, which included working for Mary Quant. He was the managing director of a luxury goods company when he was headhunted to Gieves & Hawkes.

The company has since doubled its distribution, with 20 UK outlets and 58 in Asia. Mark plans to double it again. Is America in his sights? “No, but we have many American clients. They come to us, or we go to them.”

While Gieves & Hawkes is Savile Row's oldest and largest bespoke tailor, that is only part of its business. “We also do off-the-peg and personal tailoring, where suits are individually measured but factory made. A bespoke suit is made on the premises by hand. Bespoke tailoring has moved from being a dying craft to a luxury-goods industry. Its revival is down to how people perceive luxury and, at the moment, that is having something made especially for you.

“We formed the Savile Row Bespoke Association partly to promote training. It takes ten years to train as a tailor - longer than a surgeon - and we now have 20 trainees.

“Bespoke suits cost from £3,500 up to £10,000. Our clients aren't just older, larger men, although wealth and shape grow together: many of our customers are young and svelte.

“The suits aren't cheap, but you need only a few to last a lifetime and men's fashions change very little. The coolest thing at the moment is a one-button suit, but that's an absolute classic. Otherwise, it's turn-ups or not, single or double-breasted, and waistcoats.

“I have 50 suits in my wardrobe and always wear one to work - today, it's a blue pinstripe off-the-peg - but at home in Dorset, I'm happiest in a pair of old moleskin trousers.”

Times Recommends

• Inspirational leadership
• How to get a new job
• The reluctant CEO