Marks & Spencer is set to reveal its worst trading performance in three years tomorrow (Tuesday), with non-food sales expected to plummet 7%.

Overall sales are expected to dip 3% in its first quarter with growth in its food business expected to offset the plunge.

One of the worst hit areas is expected to be womenswear, where the retailer is thought to be losing market share against its competitors. The wet weather will have exacerbated the plunge in the category.

The sales fall comes as rival Next has overtaken Marks & Spencer in market capitalisation for the first time in its history, despite having fewer stores and no food business.

M&S is now worth £5.1bn against Next’s £5.3bn.

Pressure is building on chief executive Marc Bolland with shareholder advisory group PIRC advising investors to abstain from voting in support of M&S’s remuneration report at its Annual General Meeting tomorrow (Tuesday).

Shareholders are also likely to want clarity on executive director, general merchandise Kate Bostock’s position. Speculation has been rife that the fashion boss is to depart M&S.