In flowing, cursive script, its entries reveal intricate details of how the district's pioneering homesteads were painted and wall-papered, church windows glazed, lamp posts and hitching rails restored and flagstaffs gilded.

More than just a curiosity from a bygone era, the ledger is a very personal connection to a Warrnambool business dynasty of which Mr Rule is the latest incumbent.

That dynasty, Hammonds Paints, this year marks 150 years of continuous trading by a family now in its fifth generation.

A longevity rivalled by few, managing director Mr Rule is rightly proud of the business founded by his great-great grandfather Joseph Charles Hammond when Warrnambool was just a few decades old.

One of the few surviving artefacts of its early days of trade, the ledger dates to 1890, some 16 years after the business was launched in 1874.

"It's an extremely rare achievement that one family can retain a business for that long. I feel very proud as I reflect back on five generations," Mr Rule says.

"It's not a bad effort to make it to 150."

In a nod to the contribution of employees to that success, hundreds of former and present staff and their families will mark the milestone at a function at the Warrnambool racecourse on April 6.

Employees and contractors across the business' five branches comprising Warrnambool, Portland, Hamilton, Ballarat and Colac currently number about 50.

"We really wanted to acknowledge the achievement with all our staff. It's rare that we all get together," says Mr Rule, 64, who has presided over the business for nearly 30 years, taking over in 1995 from his father John Rule whose own tenure spanned 44 years.

That family work ethic has long been mirrored by their dedicated staff, many of whom have notched up similar lengths of service.

"All businesses are reliant on their staff and staff are reliant on businesses for their livelihood. You put a lot of trust into your staff and they respond," he says.

"It's a two-way street and it works. I really care about our staff and in return they care about our business.

"We have had so many people who've worked for us for 30 to 40 years."

The resultant wealth of knowledge and experience has been the linchpin of Hammonds' long-running and hugely successful marketing slogan: "Should've gone to Hammonds".

Coined by advertising guru Marcus Tarrant in 1998 as part of a rebranding, it's a simple message, says Nick Rule, but one that encapsulates the Hammonds' point of difference to a T.

"All of our marketing is centred on the fact that we are an independent paint specialist, as opposed to a mass merchant. We trade on having the right staff and expertise, not on a price point.

"We haven't waivered from it, we haven't altered the message. It gives the business an identity. One of our strengths would have to be that we've marketed ourselves pretty well."

Where others have fallen by the wayside, it has also helped them to survive in a dramatically changed retail landscape, he says, referring to the advent of the retail giant Bunnings.

"When I first started in Warrnambool there were 11 or 12 paint outlets in town. Bunnings has had a massive impact. We are now the only dedicated paint store in town."

These days, Hammonds' market is split 60:40 between decorating (trade and personal shoppers), and automotive and industrial.

Catering to the home building trade market, it is also the district's biggest painting contractor of large commercial works such as schools, factories, offices, hospitals, theatres and law courts.

"Warrnambool has been pretty lucky over the last 30 years. We have a strong economy and there have always been some reasonable-sized construction jobs on the go," Mr Rule says, stressing that a healthy automotive sector is vital to underpinning the business.

It's a markedly different landscape from when 27-year-old Joseph Charles Hammond launched his painting and decorating business in 1874. With a population of just a few thousand the fledgling settlement of Warrnambool was still nine years from being officially proclaimed a town.

One of 11 children of Irish immigrants Joseph Robert and Helenah Hammond, young Joseph had completed an apprenticeship with Warrnambool painting and plumbing entrepreneur, William Norman, before taking on shearing and indulging his passion for horse racing for several years, one he shares with his great-great grandson Nick.

The slightly-built Joseph even made his mark riding on the flat and over the hurdles at district races.

By 1874 and now married to Margaret Fox, Joseph had returned to his trade, launching his first store and the birth of a local business icon.

Known as Hammond & Sons, the business offered signwriting, painting and decorating from premises now occupied by a launderette, north and on the opposite side of the current Fairy Street shop.

A decade later in 1884, Joseph upped stumps and relocated to the present site on the corner of Fairy and Lava streets where four subsequent generations of the family continued his legacy.

His son Thomas Samuel Hammond was the next in line, taking the reins after Joseph's death in 1932, before third generation Frank stepped up in 1945 for the post-war period.

With Frank's health failing, the call went out to his 19-year-old nephew John Rule who was then in Melbourne studying accounting and doing an internship with Dunlop. Frank's sister, John's mother Grace and a cousin took over book-keeping duties.

Returning to Warrnambool to take on the role in 1951, John came into a business that was primarily a paint contractor. In the pre-DIY days, retail trade was minimal.

Now 92, John recalls the shop back then as "basic".

"Dirt floors and lined with bales and bales of wallpaper and lining paper. There were also gallons of Rickshaw Red roof paint, made in Scotland, it was the best roof paint you could get then."

Glazing and picture framing were also services provided by the business, both of which were later sold off.

Paint was made from white lead, with colour choices limited to "PWD brown which was used on all the public works department buildings, a dark green, a white and a black. That was it," says John.

When Hammonds secured the distribution rights for a plastic paint called Spread Satin a few years later, it became a game-changer for the business and the start of a booming retail trade.

"Because it was cleaner and easier to use, this really unleashed the DIY sector. Soon after they launched rollercoaters, another boon for the DIY sector and Hammonds were early adopters," John recalls.

Expansion followed with stores opening in Portland in 1974 and Hamilton in 1988.

When John's son Nick and wife Fiona took over the business in 1995, Hammond & Sons became simply Hammonds Paints and technology was rapidly changing the way the business operated.

Joseph Charles Hammond's hand-written ledgers had long been consigned to history. Today, computer systems allow all stores to interact in real time.

The business widened its reach with the addition of stores in Swan Hill, which has since been sold, Ballarat in 2014, and most recently, the Rules' son Jeremy has joined his father in a Haymes Paints franchise in Colac.

While he's happy to have his son on board, Mr Rule says there's no pressure on any of his three children to continue the Hammonds family dynasty.

In any case, he's not planning on stepping away from the business just yet.

"The business is solid and from a management perspective, I'm happy to continue on. I love coming to work."