The blue-chip FTSE 100 index <.FTSE> ended 2.3 percent higher at 7,046.82 points, within touching distance of the record high of 7,122.74 points reached last month. It recorded its biggest one-day percentage gain since early January.

The FTSE 250 mid-cap index <.FTMC> finished 2.8 percent stronger after setting an all-time high as the election results came through and the Conservatives secured an overall majority, overturning poll predictions of a hung parliament.

Many investors had backed the Conservatives over the opposition, centre-left Labour Party which had promised tough regulation of industries such as banking, utilities, real estate and gambling which could have hit the profits of companies in those sectors.

"We are seeing a relief rally in some domestically focused names, with utilities, real estate, transport and banks having a pretty good day," Robert Parkes, director of equity strategy

at HSBC Bank said.

"But the political uncertainty isn’t going to go away. We have now got a referendum of Britain’s EU membership on the horizon."

The FTSE 100 Volatility Index <.VFTSE> slumped 28.8 percent to 11.9, the lowest since July. Trading volumes on the FTSE 100 were 184 percent of its 90-day daily average, against 128 percent for the pan-European FTSEurofirst 300 <.FTEU3> index.

Below were the big sectoral movers of the day:

* UTILITIES - The FTSE 350 Utilities index <.FTUB7500> rose 5 percent, the biggest one-day percentage gain in six years, on the prospect of less regulation in the sector. The Labour Party wanted to give the energy regulator the power to force firms to cut prices in response to falls in wholesale costs.

* Utilities Centrica (>> Centrica PLC), SSE (>> SSE PLC), Severn Trent (>> Severn Trent Plc) and National Grid (>> National Grid plc) gained 4.1 to 8.1 percent.

* BANKS - British banks <.FTNMX8350> up 3.1 percent as election results removed fears of a break-up of the biggest banks and further hikes in a tax on banks' assets. Lloyds (>> Lloyds Banking Group PLC), RBS (>> Royal Bank of Scotland Group plc) and Barclays (>> Barclays PLC) were up 3.7 to 6.1 percent.

* REAL ESTATE - Property stocks were up as Labour's "mansion tax" proposals and "use it or lose it" policy for developers who own land that could be used for homes had unnerved investors. On the other hand, the Conservative Party plans to expand a "Right to Buy" programme to allow people living in social housing to purchase their homes at a discount.

* Housebuilder Berkeley Group (>> Berkeley Group Holdings PLC), Estate agents Savills (>> Savills plc), Country Countrywide (>> Countrywide plc), Foxtons (>> Foxtons Group PLC) and online property search company Zoopla (>> Zoopla Property Group PLC) climbed 3.8 to 9.9 percent.

* BETTING FIRMS - Ladbrokes (>> Ladbrokes PLC) surged nearly 10 percent, while William Hill (>> William Hill plc), Betfair (>> Betfair Group Ltd) and Bwin.Party (>> Bwin.party Digital Entertainment Plc) rose 3.8 to 9.9 percent>. Labour had wanted a new levy on online betting.

* ZERO-HOUR CONTRACTS - Sports Direct (>> Sports Direct International Plc) rose 4.6 percent. It is a large user of zero hours contracts, and was seen as being under threat in the event of a Labour-led government.

* BUS COMPANIES - Stagecoach (>> Stagecoach Group plc), Go-Ahead (>> Go-Ahead Group plc), National Express (>> National Express Group PLC) and FirstGroup (>> FirstGroup plc) advanced 3.5 to 6.6 percent. The Labour Party had planned a regulated service, with local government setting fares and routes.

(Reporting by Atul Prakash; Editing by Alison Williams)

By Atul Prakash and Sudip Kar-Gupta