Moss Bros, which is better known for suits, plans to double the number of stores to around 50, which will include more branches outside its London and South-east stronghold. Currently there are no Blazer stores in cities such as Birmingham, Leeds and Sheffield: "You've got to go where the action is," said Moss Bros chief executive Rowland Gee.
More lower-price items will be added as well as "formal corners" that will sell dinner jackets. Blazer's own brand, De Havilland, will be emphasised, though some up-market brands such as designer jeans may be added.
Mr Gee said Moss Bros was buying Blazer to complement its other chains, which include Moss Bros, the Suit Company and Cecil Gee, all dominated by formal wear. Moss Bros had been tipped as a possible buyer for Austin Reed, the up-market retailer whose shares have been rising strongly in recent months.
"Casual wear is a growing market and Blazer is a very strong casual wear brand, particularly in the 25-54 age group," Mr Gee said.
Blazer was founded in London's Covent Garden in the early 1980s by David Krantz, who now runs Racing Green. It was acquired by Storehouse, which was then run by Sir Terence Conran. It has always struggled to make a profit and last year recorded profits of just pounds 400,000 on sales of pounds 14.8m.
Moss Bros is only acquiring the stores, stock and staff of the business and not the head office, warehouse or other systems. With lower central costs and more lower-priced items to increase shopper traffic, Moss Bros hopes to improve the group's financial performance.
Moss Bros has financed the deal through a placing of 622,807 new shares.
Storehouse has been looking to sell the company as it concentrates on BhS and Mothercare. It first put the chain up for sale in 1992 but failed to find a buyer at an attractive price.
Storehouse will book a pounds 5.1m exceptional charge on the deal, representing a goodwill write-off from the original purchase. Storehouse shares added 7p to 325p. Moss Bros fell 32p to 1163p.
Storehouse chief executive Keith Edelman received total pay of pounds 910,000 last year, boosted by a pounds 384,000 long-term bonus. This compares with a total of pounds 610,000 the previous year. Group development director Steve Bedford saw his pay jump from pounds 436,000 to pounds 556,000, due to a pounds 306,000 bonus. Finance director Dick Steele's pay rose from pounds 294,000 to pounds 378,000.