The subtilties of the British English accents, and the way they change from generation to generation, are very difficult to pinpoint. Prince William, of course, speaks i clear standard upper class English. However, it is not the same accent as the Queen Mother or even the Queen has, as it has been influence by current Standard English. There is, however, no regional influence is PW's accent.
Catherine Middleton's accent has probably been honed by being at a good school, which will largely iron out any slight regional inflexion she might have had as a child. I don't know enough detail about her early life to be sure of what influences she may have had. It is, however, good standard English, and, on what I have heard, does not have any obvious regional accent.
Catherine Middleton's accent has probably been honed by being at a good school, which will largely iron out any slight regional inflexion she might have had as a child. I don't know enough detail about her early life to be sure of what influences she may have had. It is, however, good standard English, and, on what I have heard, does not have any obvious regional accent.