Marks & Spencer is to open outlet shop-in-shops in some of its high street stores in a departure from its traditional practice.

The format made its debut on Monday in Lewisham, south London, where the first floor of the store now carries clearance lines and the ground floor continues to stock the latest season’s ranges and food.

The same model will be adopted in three other locations – Wood Green in north London, Stevenage and Slough – and will all be introduced in March.

M&S head of outlets Nick Bullock insisted the conversions do not form part of a bigger outlet opening programme in conventional stores.

He said: “We have identified four stores in locations where we think shoppers would benefit from a choice between our great value outlet merchandise and the existing food and clothing offer. There are no plans to make this change in any further stores.”

Analysts believe the initiative reflects how tough trading is at the moment for mid-market store groups and makes sense on a fiercely promotional high street.

Numis analyst Andy Wade said: “It’s probably a recognition that they need to be more flexible.” He dismissed the idea that the venture indicates M&S may have a pressing stock problem, because opening the outlets over a period of months would not provide a fast enough clearance channel in such circumstances.

The affected M&S stores are typically in shopping areas where there is a strong value retailer presence. In Wood Green, for instance, there is a Matalan clearance store close to M&S.

M&S has 40 outlet stores in total, including some in high street locations.