Some of my earliest shopping memories are of trips to Marks & Spencer in Chichester with my mother. I can remember the car park, the shopping trolley ramp, the smell entering the store and the unmistakeable hum of the refrigeration units in the food aisles.

In the 1970s M&S had a seemingly unassailable place in the hearts as well as the minds of millions of British shoppers…

In fact, so great was the company’s brand equity in the Shippam household, and no doubt many others too, that my mother called Marks & Spencer “the good shop”. But it also went by the monicker of Marks & Sparks, as well as M&S. Even today I struggle to think of another retailer that commands not one, but two or three nicknames among its customers.

When I was studying for my MBA at Warwick Business School in 1997 our Marketing Professor, the late Peter Doyle, singled out Marks & Spencer. He trumpeted its “28 unbroken years of profit growth”. So this was a company that commanded respect from academics as well as shoppers.

Unbeknown to him at the time, Professor Doyle was “calling the top” for Marks & Spencer. The company’s record pre-tax profit of £1.16 billion was achieved in 1997/98 (source: Wikipedia). They came close exactly a decade later (£1.13 billion), but since then pre-tax profits have never breached £800 million.

This performance has been reflected in the share price: you could pick up M&S shares for around 250p in 1991, 2001, 2009, 2019…and today. This performance masks many changes, but I still think it reflects the tale of a company that lost its way.

One of the central challenges Marks & Spencer has found itself wrestling with is the need to stay close to its existing customers whilst appealing to new ones too. I think there are vital lessons here for businesses across many consumer sectors.

For M&S the challenge was keeping pace with both the way people shopped and what they wanted to buy. The convenience of a store that sold everything from pants to pork pies has been challenged by more specialist and nimble competitors, fast fashion, online distribution and a property estate focused on a declining British High Street.

But after 25 years of struggling to reinvent itself, M&S may have turned a corner under current Chairman and CEO, Archie Norman and Stuart Machin. After a stellar stock price performance and a four year absence, M&S has recently returned to the FTSE100 index of leading UK companies.

There are many possible drivers behind the apparent recovery, both consumer-facing and behind the scenes, and time will tell if this marks a turnaround rather than just another turn. But I think rediscovering their customers lies at the heart of the company’s recent performance.

So I have no idea whether Norman and Machin have done enough to end the three decade rollercoaster ride in the M&S share price, but the company offers a lesson for every business about the need to adapt to remain competitive and relevant to customers.