Mr Griffiths, 54, of Chiswick, said: "There are no words to explain how I feel. People ask if there is anything they can do but the one thing I need they can't do - bring Sam back. I spoke to him after 12.30am to say happy New Year and he was calm and relaxed. He said, 'I love you dad'. I said I loved him and told him to take care. Typically, he ignored what I'd said to him. It was a tragic accident."