Marks & Spencer directors have ramped up their shareholdings, sending a message to investors that they remain convinced of the retailer’s strength following reaction to today’s trading update.

The retail bellwether’s share price went into tailspin this morning after a like-for-like sales drop over the key Christmas period was disclosed.

M&S shares plunged by almost 20 per cent to a level close to the 400p offered by tycoon Sir Philip Green in his abortive bid in 2004. However, M&S bosses, including chief executive Sir Stuart Rose and chairman Lord Burns, have snapped up more than 300,000 shares.

Rose alone spent more than£1 million, buying 250,000 at 410.66p a share. Burns acquired 24,316 at 411.25p, while new food supremo Steven Esom bought 24,360 and international boss Carl Leaver snapped up 17, 954.

Kaupthing analyst Matthew McEachran believed the buying indicated that M&S chiefs believe there is the opportunity to regain ground by taking action on costs and margins. He noted that they resisted the chance today to encourage analysts to push down expectations.

He said: “They had an opportunity to bottom out forecasts, but they kept their powder dry and now they’ve bought stock.”

McEachran still expects M&S to deliver full-year profits of just more than£1 billion.