British utility companies breathed a sigh of relief on Dec. 13, after a crushing general election defeat for the opposition Labour Party meant plans to renationalize the industry went up in smoke.

Voters delivered a landslide victory for Prime Minister Boris Johnson's ruling Conservative Party, sending shares in National Grid PLC and SSE PLC, two of the largest owners of power and gas grids in the U.K., up by around 7% and 9%, respectively, at 11 a.m. in London.

Labour, led by Jeremy Corbyn, was planning to take both transmission and distribution grids back into public ownership if it came into power, along with retail energy providers, water companies, rail networks and Britain's postal service. The specter of nationalization had hung over the sector since at least the start of the year, although polls indicating a Conservative victory had lifted some of the gloom in recent months.

"The Labour Party's dismal performance means that the risk of nationalization has been taken off the table for good," analysts at Alliance Bernstein wrote in a note. "We see this as very positive for the U.K. regulated utilities."

Investors in companies that own and operate parts of the grid, also including Spain's Iberdrola SA and U.S.-based PPL Corp., worried a nationalization could leave them out of pocket. Some operators had recently made moves to protect their assets by moving ownership abroad in preparation for legal challenges.

But the Conservatives gained at least 66 seats in the poll, securing a comfortable majority in parliament that quashes any prospect of Labour's policy coming up for a vote, and likely paves the way for a negotiated exit from the EU at the end of January.

Britain's largest retail energy suppliers also gained on the news, after Labour had expanded its nationalization plan to encapsulate them in September. Centrica PLC, battered by investors this year, was up around 8% while Electricité de France SA rose 2% in Paris. Shares in Germany's E.ON SE, which recently acquired a second British retail supplier by swallowing rival innogy SE, were up by close to 1%.

Water companies United Utilities Group PLC and Pennon Group PLC also saw their stocks climb by 8% and 9%, respectively, although Ahmed Farman, an analyst at Jefferies, pointed out that any gains could be short-lived because of a likely punitive regulatory update from Britain's water services authority on Dec. 16.

Bernstein analysts also noted that a Conservative win brings the promise of a relatively lower corporate tax rate of 19%, compared to Labour's 20%-28% and the 20% proposed by the Liberal Democrats. "Has Christmas come early? It has if you want to buy U.K. stocks," analysts at the bank wrote in a note, also pointing to banks, builders and retail companies as likely winners.

The result also confirms the U.K.'s net-zero emissions target for 2050, a boon to both renewables developers and companies like National Grid, responsible for the necessary grid enhancements. Ahead of the election, the Conservatives pledged to raise the country's 2030 offshore wind development target by 10 GW to 40 GW if the party was elected.

The higher goal is a positive development for large wind farm builders including SSE, Germany's RWE AG and Denmark's Ørsted A/S. Labour had plans to build 52 GW of new offshore wind farms by 2030 under majority public ownership, while boosting solar rooftop installations and electric vehicle charging.