Couples in an existing same-sex civil partnership may now convert their civil partnership to a marriage, as long as the civil partnership took place in England or Wales (or overseas in a consulate or armed forces base where the civil partnership was registered according to the laws of England and Wales).
You do not need to convert your civil partnership with the same local authority who registered it. For example, if your civil partnership took place in Surrey your conversion can still take place in Westminster.
Converting your civil partnership to a marriage is a simple administrative process which will take place at the Westminster Register Office on Harrow Road.
There is currently no provision for couples in an opposite-sex civil partnership to convert their civil partnership to a marriage.