Marks & Spencer has traditionally been guarded about disclosing figures on food availability – and with good reason.

It is at a natural disadvantage to other food retailers because of the high proportion of fresh products it stocks and by its own omission, its performance in the past has been less than stellar.

But yesterday in its full-year results presentation, M&S took the unusual step of revealing not just the relative progress it has made on availability, but the actual numbers.

Perhaps that is because the high-street icon now has something to shout about. It said availability had risen seven percentage points over the last three years to 93%.

That is well ahead of the target, set in 2010, of a five percentage point improvement over five years.

And the work doesn’t stop there. M&S said it was now looking to improve availability to 96% over the next three years, which would put it in line with, if not ahead of, the big four supermarkets – despite its bias towards fresh food.

Average availability across the big four in 2012/2013 was 95.7%, according to data compiled from The Grocer 33.

The continued improvement is particularly impressive given that M&S is putting more strain on availability by getting more of its range into stores. Yesterday, it boasted it had increased the number of stores selling the full range of M&S food lines to 110.

But improving availability and putting a bigger portion of the range into stores is really driven by the same agenda. It is about ensuring that when customers come into stores, they find what they are looking for. Not only does this prevent lost sales, it keeps the customer happy.

In recent years, M&S has benefited from having a clearly differentiated and upmarket offer giving it protection from the threat of the discounters, but food director Steve Rowe and his predecessor John Dixon deserve credit for getting the basics of retail right as well.

M&S has grown like-for-like food sales for 18 consecutive quarters and this financial year sales grew 1.7%. The step change achieved in availability is an important, but often overlooked, part of this story.