They used to say you really never leave the KGB. Or the CIA, for that matter.

Apropos of nothing, it’s hard to think of many people who’ve jumped ship early from Tesco in recent times and gone on to genuinely bigger and better things. That says plenty about the retailer’s track record of retaining senior talent and planning for succession, although its leaders continue to be popular targets.

News of Laura Wade-Gery’s defection to Marks & Spencer has raised plenty of eyebrows – as much for the timing of the move as anything else.

It certainly must have come as a surprise to Philip Clarke, who last month named Wade-Gery on an expanded executive committee that gave greater prominence to the supermarket’s online operation.

The Tesco.com chief was handed a new brief as executive director for UK non-food, in what was widely regarded at the time as a promotion. But perhaps Wade-Gery’s thinking was closer to those who interpreted it as a sideways move. Maybe she had her eye on an even larger role in the post-Leahy era, considering Wade-Gery had long been tipped for greatness.

Either way, her arrival at Marks & Spencer is a coup for Marc Bolland – and a move that emphasises his determination to get the high street giant punching its weight on the web.

In the traditional manner of Cold War defectors, Wade-Gery said all the right things about her adopted motherland.

“M&S is an iconic brand,” she said, trumpeting its “huge potential to develop a multi-channel offering for customers”.

While the usual issues over basket size means M&S remains unlikely to move into online grocery, Wade-Gery might want to keep an eye out for polonium pizzas and exploding cigars, just in case.

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