Lady Watts, speaking at the family's Oxfordshire home, said: 'We still have no idea where he is or what's happened to him. It really is quite terrible. He's the most unlikely person to have done something like this. I just can't understand it.
'He must have had some sort of nervous breakdown that we didn't know about. He's probably just wandering about somewhere in a confused state.'
She said had she hoped her husband, who was last seen by his chauffeur who dropped him at his London flat last Tuesday, might have travelled to their home near Charlbury, Oxfordshire.
Lady Watts has discounted reports her husband was 'troubled' after being told he was suffering from Parkinson's disease. She said Sir Roy's condition was first diagnosed two years ago and it was in its mild, early stages.