U.K. smart meter firm Calisen Group Holdings has called on Simpson Thacher & Bartlett to advise on its anticipated float on the London Stock Exchange, in what is expected to be London's first initial public offering (IPO) this year.

The Manchester-based company is owned by private equity firm KKR and is the leading owner and manager of essential energy infrastructure assets. Calisen's operations consist of two business units, Calvin Capital and Lowri Beck.

According to a statement announcing its intention to float, Calisen says it expects to raise around £300 million, alongside an offer of existing shares to be sold by certain existing shareholders.