The FTSE 100 index added 43.20 points, or 0.7%, to 5,877 points today, led by Compass Group.
The catering supplier gained 3.53% to 271.50p following the sale of its travel concessions unit.
Mortgage lender Northern Rock rose 3.80% to 1,038p on the back of reports it could consider a possible merger with Bradford & Bingley. Bradford & Bingley advanced 0.97% to 469.25p.
Supermarket William Morrison rose 3.73% to 201.75p after speculation the group is being targeted by a consortium of private equity houses looking to make a £6bn bid for the firm.
BP advanced 1.27% to 638.50p, Royal Dutch Shell gained 1.43% to 1,918p and BG Group rose 1.87% to 736p after crude prices slipped from their recent peaks but remained steadfastly higher on the day, down just 8 cents at $73.85 a barrel.
Cairn Energy topped the fallers, down 1.78% to 2,154p, after disappointing news on several of its appraisa wells.
In the US, the Dow Jones Industrial Average index has gained 54.89 points, or 0.5%, to 11,205.11 points on speculation a manufacturing report will give the Federal Reserve more leeway to hold off on raising interest rates.
General Motors has added 36 cents to $30.15 after Banc of America raised the stock to "neutral" from "sell" on the prospect Renault SA and Nissan will invest in the company.
Alcoa has gained 77 cents to $33.13 on reports the aluminum producer may attract takeover bids from miners such as BHP Billiton and Rio Tinto Group.
Citigroup has risen 32 cents to $48.57 on reports shares of the financial services company may climb to $60 as it expands overseas and looks to Internet banking.
Newmont Mining has added $1.73 to $54.66 as the price of gold rose to the highest in almost a month in London.IFAonline
Chris St John to take over £3bn UK Select Opps
The majority of financial advisers (85%) believe the number of self-invested personal pension (SIPP) providers will continue to fall in the coming year, according to Dentons Pension Management research.
Short-term noise or something sinister?