England and Wales have marked a new era in which heterosexual couples can choose to have a civil partnership instead of a marriage.
The change, mandated by Britain's Supreme Court last year, took effect Tuesday.
The groundbreaking case had been brought by Rebecca Steinfeld and Charles Keidan, who were among the first to form a civil partnership under the new rules.
They were joined by their two children for the partnership formed at the Kensington and Chelsea Register Office in central London.
Steinfeld, 38, called it "a unique, special and personal moment for us" that had been "rooted in our desire to formalise our relationship in a more modern way, focus on equality and mutual respect."