National Grid is one of the world’s largest publicly listed utilities focused on transmission and distribution of electricity and gas in the United Kingdom and the United States. It plays a vital role in connecting millions of people to the energy
they use safely, reliably and efficiently.

It finances its operations from trading and debt. It currently has Net debt of £28.6bn as of March 31st 2021. It has to pay back this debt from now to the end of 2057.

The graph below shows that maturity profile.

https://www.nationalgrid.com/investors/debt-investors/debt-information