A man says he was acting in self-defence when he stabbed a close friend seven times and left him in a pool of blood, a jury has heard. Ajay Porter, of no fixed address, is on trial accused of murdering Derek O’Hare, 66, outside his home in Anstee Road, Dover, last December. The 36-year-old denies charges of murder and possessing an offensive weapon, claiming his actions were reasonable and necessary to defend himself. Opening the case on Tuesday, prosecutor Nina Ellin KC said the defendant’s actions constituted a “vicious and merciless attack”. “Shortly after 10pm on Monday, December 11 last y…