As St Valentine's Day approaches, Katherine Jenkins visits the Tower of London where it is thought the earliest recorded valentine was written in the 15th century. She explores the tower's two beautiful chapels and meets the first female beefeater. We find out about Christian digital dating and join two young people hoping to find their valentine. Finally, Sean Fletcher hears from the couple passing on the secrets of their long and happy marriage to those planning to tie the knot, and Gregory Porter sings about love.