Shurgard has agreed to spend 11.10 pounds in cash for each Lok'nStore share, which it said represents a 15.9% premium to its closing price on April 10.

"The acquisition will allow Shurgard to increase its footprint in the two most attractive target markets outside of London," the company said in a statement.

Expected to be completed in July, the deal will add 32 Lok'nStore properties in the South East of England and five more in Manchester.

"It will double its size in the UK from 48 stores to 100 (including pipeline). It fits in their strategy to focus on large cities," said analyst Wim Lewi of KBC Securities.

Lewi added that Lok'nStore's decision to sell might have been guided by lower occupancy rates, for which Shurgard benefits from its platform strategy.

Analyst Vincent Koppmair from Degroof Petercam said the size of the deal "is just bigger than expected" and that it "appears digestible" for Shurgard.

The company also said it will assess duplicative job roles in the merger, even if no firm decisions have been made yet.

"It will likely result in the loss of the majority of roles across Lok'nStore's administrative and head office functions," Shurgard said in a statement.

Lok'nStore shares, which will be delisted once the deal closes, rose nearly 18% to 1,13 pounds at 1111 GMT, while Shurgard's rose 0.74% to 40.85 euros.

($1 = 0.7977 pounds)

(Reporting by Iain Withers and Nathan Vifflin; editing by David Goodman and Devika Syamnath)

By Nathan Vifflin