I have a doubt. If Princes William or Harry had married a princess of another kingdom, say Victoria or Madeline, would those princesses have kept their original titles?
In the past, foreign princesses who married into the British royal family did not use their foreign titles in the United Kingdom, so I would say no.
Of course I believe that, unless rescinded under domestic law, they keep their titles in their original countries as those are outside British jurisdiction.
Out of interest, why is it that the Earl of Wessex's son is so commonly referred to in the press and by the public as James, Viscount Severn, instead of his correct style of Viscount Severn?
I think James, Viscount Severn, is also a correct style. In fact that is how peers and eldest sons of peers are referred to in the identification page of their UK passports, i.e. [Forename] + [Title (or Courtesy Title)] in the surname field.
Likewise, for a British prince, you can either use HRH The Prince of Wales and HRH The Duke of Cambridge,
or HRH The Prince Charles, Prince of Wales and HRH Prince William, Duke of Cambridge. It is simply a matter of using the short or the long style. The only difference between princes and peers in that respect is that, for princes, under the LPs of 1917, the forename must be preceded by the prefix "Prince" and the style of "Royal Highness".
Since peers, unlike princes, also use a family name, that can be also added to the long style, e.g. Edward Fitzalan-Howard, Duke of Norfolk, but, in British passports, that is done only in the Observations Page. In the identification page itself, the family name is omitted and replaced by the title, which is odd by international standards (I wonder how the EU felt about that !).
Note that, in announcements of appointments to the royal orders of the knighthood, the following format is used for peers: [Prefix (e.g. The Most Noble or The Right Honourable]+ [Forename(s)]+[Family Name] + [Title designation] +[Post-Nominal Letters], when the family name is
not part of the title designation, or [Prefix]+ [Forename(s)] + [Title Rank]+[Title Designation including the family name] +[Post-Nominal Letters] otherwise, see some examples below extracted from the London Gazette.
Central Chancery of the Orders of Knighthood
St James’s Palace, London SW1
23 April 2003
The Queen has been graciously pleased to appoint the undermentioned to be Knights Companions of the Most Noble Order of the Garter:
The Most Noble Gerald Cavendish Grosvenor, Duke of Westminster, OBE, TD, DL.
The Right Honourable Frederick Edward Robin, Baron Butler of Brockwell, GCB, CVO.
The Right Honourable John, Baron Morris of Aberavon, QC.
THE MOST ANCIENT AND MOST NOBLE ORDER OF THE THISTLE
Chancery of the Order,
Court of the Lord Lyon, Edinburgh
29th November 1996
The QUEEN has been graciously pleased to make the following appointments within the Most Ancient and Most Noble Order of the Thistle:
The Right Honourable John Campbell ARBUTHNOTT, Viscount of Arbuthnott, CBE, DSC, to be a Knight of the Order;
The Right Honourable Robert ALEXANDER Lindsay, Earl of Crawford and Balcarres, P.C., D.L., to be a Knight of the Order;
