The announcement that the Duke and Duchess of Cambridge are expecting a child is wonderful news and a boost to the monarchy.

It is also a reminder that Canada and other Commonwealth realms have begun important work to modernize the monarchy but so far have failed to finish the job.

Last year, the leaders of the 16 realms agreed to end the archaic rules that give male children priority over female children as heirs to the throne and prevent those heirs from marrying Roman Catholics. But the change requires Canada, among the other nations for whom the Queen is their head of state, to adopt legislation to that effect, and not even Britain has done so yet. Time to get moving.

Not to say that the matter has been made pressing for lack of an heir. There are two male heirs to the throne standing by — Prince Charles and Kate’s husband Prince William — and neither got there at the expense of an older sister: Each is a first-born child.

What makes it pressing is that the change would come into effect if Kate and William were to have a daughter and, in doing so, would dramatically modernize the monarchy in one stroke. The monarchy has worked hard to advance and adapt ever since the death of Princess Diana in 1997, but the fact remains that centuries-old laws about male primogeniture are a hindrance to progress. …

As for the ban on marrying Catholics, the need to remove such an intolerant requirement is equally as obvious in today’s world. It would be a great day for the monarchy if, in roughly six months from now, it is confirmed that a first-born baby girl is no longer prevented from taking the throne because of her gender, and that the religion of her eventual husband is also not a bar to her ascension.

– The Globe and Mail, Toronto, Dec. 4