Ser Alton Lannister recalls squiring for his distant cousin Ser Jaime Lannister at the tournament. Jaime defeated Ser Balon Swann. The day was one of Alton's proudest achievements and he was disappointed when he had to leave the field to eat at the periphery of the wedding feast.
In the books
In the A Song of Ice and Fire novels, there is a character named Willem Frey but he is a young grandson of Lord Walder Frey and the second son of Ser Cleos Frey (the analogous character of Ser Alton Lannister) and Jeyne Darry. He serves as a page at Ashemark.
- Willem Frey at A Wiki of Ice and Fire (MAJOR spoilers from the books)