The King’s planned visit to America in late April comes 50 years after his mother navigated the same diplomatic course. If he can bring to bear even a fraction of the charm Queen Elizabeth II did, he will have served Britain well, says Hugo Vickers . But Trump is no Gerald Ford, who was known as ‘the nicest guy in Washington’ F or some weeks now, the British embassy in Washington and the royal household in London have been honing and fine-tuning plans for the King’s state visit to America, even