Deuteronomy 25: 5. But it applies only when the widow and her husband were childless. Then his brother must take her as his wife and take on the duties of the brother.
I think hc is correct the Marriage act 1949 allowed this and of course as VHG says it was done by Henry V111, but I think he claimed his Brother’s marriage had not been consummated.
In 1994 the Act was extended to permit marriage to take place in other locations.