The mid-cap index rose 34.9 points, or 0.2%, to 19,264.6 with Tullow Oil the biggest gainer, up 5.7%.

The blue-chip FTSE 100 index ended the day flat, reflecting broadly flat European markets.

It was down less than 1 point at 7,348.9 despite strong showings from retailers.

Tesco rose 2.4% after a court approved a deal between Britain's biggest supermarket chain and the Serious Fraud Office to settle an investigation over a 2014 accounting fraud.

Primark owner ABF and Marks & Spencer also gained, climbing 3.8% and 2.5% respectively.

Miner BHP Billiton did well after one of its shareholders pressured it to adopt a restructuring plan.

The mining giant's shares rose by more than 5% before closing up 2.3% after hedge fund Elliott Advisors said it had sent the plan to the firm's directors.

It would involve demerging BHP's US oil business and returning more money to investors.

BHP rejected the idea: "We have concluded that the costs and associated risks of Elliott's proposal would significantly outweigh any potential benefits."

Meanwhile, shares in Barclays ended 0.4% higher after the bank said regulators were investigating its chief executive over the handling of a whistleblowing incident.

The investigation relates to attempts by Jes Staley last year to identify the author of a letter by a whistleblower.

The bank said Mr Staley had their full confidence and should remain as chief executive.

On the currency markets, the pound rose 0.4% against the dollar to $1.2419 and gained 0.3% against the euro to 1.1711 euros.