It would have been one of Queen Elizabeth II's final birthday messages, which were sent to those celebrating their 100th and 105th birthday - and every year thereafter.
Hoare, who turned 100 on Sunday, told the BBC: "It makes me quite tearful. I am a royalist, old-fashioned. I was [surprised]. What an honour."
She added: "I very much admired [the late Queen] and all she did.
"So when she went it was a sad moment but she didn't go before she sent me this. I wasn't sure that I would get it but I was thrilled when I did."
The message is already in a frame on Hoare's wall, according to the broadcaster.
Hoare's niece, Sue Beckett, added: "For decades she talked about receiving a telegram from the Queen and was devastated to hear the news… but her telegram arrived [on Friday] and she was ecstatic."
It is thought the late Queen sent hundreds of thousands of telegrams to people in the UK to mark their 100th birthday over the course of her lifetime.
