Thomas Kingston died from a “traumatic wound to the head” with a gun alongside his body, RadarOnline.com has learned. Kingston, a member by marriage of Britain’s royal family, who was the husband of Lady Gabriella Kingston and former boyfriend of Kate Middleton’s younger sister, Pippa, was tragically found dead at his parents’ home located in a Cotswolds village on Sunday. The 45-year-old was discovered with a “catastrophic head injury,” the coroner determined, according to the UK Telegraph. Kingston died by apparent suicide, according to an inquest released Friday. Katy Skerrett, the senior c…