Daniel Radcliffe had crush on Helena Bonham Carter while filming Harry Potter

Daniel Radcliffe had a crush on Helena Bonham Carter when they co-starred in the Harry Potter franchise.

In a clip from the upcoming Harry Potter 20th Anniversary: Return to Hogwarts TV special, the 32-year-old actor read a letter he wrote to his co-star.

"Dear HBC," the Miracle Workers star began. "It was a pleasure being your co-star and coaster in the sense that I always ended up holding your coffee."

The 55-year-old actress, who appears with him in the clip, encouraged him to keep reading through his embarrassment, saying, "You can share" with a laugh.

"I can. I can share this now," he said before continuing. "I do love you and I just wish I had been born 10 years earlier (so that) I might (have had) a chance. Lots of love and thanks for being cool."

Although The Woman in Black star never had success with Bonham Carter, who played Bellatrix Lestrange in the series, he admitted to having his first kiss while filming the franchise.

"Every part of my life is connected to (Harry) Potter," the actor recalled. "My first kiss is connected to someone here. My first girlfriends were here. It all spirals out from the part of the set somewhere."

Harry Potter 20th Anniversary: Return to Hogwarts TV special airs on 1 January.