Vita said:
It would be great if Harry got Duke of Cumberland. I've always loved that title for some reason. Maybe it's because of all the historical romance novels I've read and there is usally a Duke of Cumberland in them. In any case, I didn't know that two sons could be a Duke. I thought the title of Duke always went to the eldest and the spare and those there after got to be earls, viscounts, and so on.
That applies to non-royals and the descendents of royal dukes
The sons of monarch tend to be created dukes in their own right - e.g the present Dukes of Gloucester and Kent are grandsons of a monarch as their fathers were brothers and both these brothers were created dukes in their own right by their father, George V, who also created his second son Duke of York but that title merged with the crown in 1936.
Going back to Victoria the sons of the monarch have been created the following dukes
Alfred - Edinburgh
Arthur - Connaught
Leopold - Albany
George V created his sons dukes as follows
Albert - York (later George VI)
Henry - Gloucester
George - Kent
John didn't live to adulthood so was not created a duke of anything.
I haven't included the eldest sons of these monarchs as they inherited the Dukedom of Cornwall on either birth (Edward VII) or accession of father (George V and Edward VIII).
Victoria created her grandsons through her eldest son Dukes in her lifetime - Eddy - Duke of Clarence and Avondale and George - Duke of York.
The present monarch has only created one son a Duke - Andrew as Duke of York but her eldest son inherited the Dukedom of Cornwall on her accession and there is an agreement in place to create Edward Duke of Edinburgh on the death of both the present Duke and the Queen when the title merges with the crown on Charles accession.
If Harry marries in the reign of the present Queen I would expect him to get a dukedom as he will be the second son of the monarch at some stage - as was the Queen's father - created Duke of York, the Queen's grandfather - also created Duke of York, but that title is currently held by the Queen's own second son so shouldn't be available for regrant in the lifetime of the present Queen.
I would also expect William to be given a Dukedom at some stage in the future, again probably on marriage.
These are the only two of the Queen's grandchildren I would expect to receive titles in her reign.