The FTSE 100 index closed up 72.53 point at 6,437.80.
BT Group was the top riser in the index, climbing 3.5% after the competition regulator gave provisional clearance to its takeover of mobile phone operator EE.
Share of gold miners also rose on the expectation that the US Federal Reserve would not increase rates.
Fresnillo rose 4.6%  and Randgold shares gained 3.8%. The gold mining companies were the best performing shares of the day.
Shares in engineering firm Meggitt plunged nearly 20% after it issued a profit warning.
The firm said trading saw a "marked deterioration" last month, and in the third quarter military sales fell 2% while energy sales dropped 16%.
Meggitt said full-year underlying operating profit was set to be "meaningfully below" consensus forecasts of £369m.
Shares in Lloyds Banking Group dropped 4.3%. While the bank reported a rise in third quarter pre-tax profits, underlying profits fell and the bank took another £500m provision to cover PPI mis-selling costs.
Shares in Next slipped 0.5%, even though the clothing retailer raised its full-year sales and profit forecasts slightly.
Next is now predicting pre-tax profits of between £810m and £845m, compared with its previous forecast of £805m-£845m.
Sales growth is now forecast to be between 4% and 6%, against an earlier estimate of 3.5%-6%.
Shares in Trinity Mirror rose 7.3% after the newspaper publisher said it had agreed to buy Local World in a £220m deal. The purchase will make the company the UK's largest regional news publisher.
On the currency markets, the pound fell against the dollar to $1.5328 and ended higher against the euro to €1.3840.
(Close): Shares in London rose on Wednesday on the back of gains by gold mining companies and BT.