James is Prince Edward and Sophie's second child
The Queen and Duke of Edinburgh have attended the christening of their youngest grandchild, the son of Prince Edward and the Countess of Wessex.
James Alexander Philip Theo, who is four months old, has been given the title Viscount Severn.
The ceremony took place in a private chapel at Windsor Castle.
James wore a replica of the satin and lace royal christening gown, which was made in 1841 and had been used for every royal christening until this one.
The new robe was commissioned by the Queen to preserve the original.
Eighth in line
Rt Rev David Conner, the Dean of Windsor, conducted the service.
In attendance were James's godparents Denise Poulton, Jeanye Irwin, Alastair Bruce, Duncan Bullivant and Tom Hill.
The couple's second child was born by caesarean section at Frimley Park Hospital in Surrey and weighed 6lb 2oz.
Edward and Sophie's daughter, Lady Louise Windsor, now four, was born prematurely after the countess became dangerously ill, but James's birth passed without complication.
There was a scare in January when he was taken to hospital after falling ill with a minor allergic reaction.
James is the eighth in line to the throne and the first male grandchild for the Queen and Duke of Edinburgh since Prince Harry was born.