Mavis finds a piece of stone cladding in the lounge and the window broken. Derek suspects the twins. The Duckworths celebrate their 33rd wedding anniversary. Mike moves his desk onto the shop-floor to Ivy's annoyance. Derek accuses the twins of throwing the stone but they deny it. Jim tells Derek the twins were watching TV with him when the window was broken and threatens Derek when he suggests that he's lying to protect them. Bet wonders who Tina's wealthy new boyfriend is and worries that he's married. Steph tells Mavis that Vera broke the window. Derek is afraid to accuse Vera after his confrontation with Jim but Mavis makes him. Mike works late going through tomorrow's business to undercut Ralph Dobson. Vera denies throwing the cladding but reveals her guilt when she accuses Jack of sh