Historic Italian restaurant chain Spaghetti House has shut all of its restaurants after its parent company entered administration . Bosses attributed the closure to escalating costs and challenging trading conditions amid "global instability". All 101 staff members at the company have been made redundant. Lavval Restaurants, the group behind the London brand, appointed corporate finance specialist BTG as administrators last week. It is understood that the company had already closed three locations in recent months, in Mayfair, Goodge Street and Fitzrovia. Administrators have since shut the remaining five central London sites. Spaghetti House was founded by Simone Lavarini in 1955 and remained owned by the family. The group’s Knightsbridge branch was in the media spotlight in 1975 when three robbers took the restaurant’s staff hostage following a failed robbery.…