The FTSE 100 index of bluechip companies was flat at 0710 GMT, while the FTSE 250 midcap index was 0.1% lower.
Oil majors Royal Dutch Shell Plc and BP Plc were higher, tracking gains in crude prices on concerns that Iran's seizure of a British tanker last week may lead to supply disruptions in the Middle East.
Energy company Centrica Plc slumped 1.5% after the Times reported that the company was set to cut its dividend and put its oil and gas business up for sale.
Among midcaps, Ted Baker Plc added 3.2% after the Times reported https://www.thetimes.co.uk/article/former-boss-ready-to-dress-ted-baker-for-private-party-xd6583zmk that the company's founder Ray Kelvin was considering plans to back a private equity buyout of the company.