@chopc
No the opposite! It is very good idea. Durham (History) and converting to law are a good mix! DD's boyfriend did just that and other friends of hers. It is an excellent place to go. DD's boyfriend did MLaw at Cambridge but started with an undergrad degree from Durham (History). If Oxbridge was not possible, Durham is a great place to go pre law conversion. There is quite a lot of evidence that Law recruiters at the London firms/barristers chambers still recruitfrom the top few universities so I always think it is best to give yourself the best possible chance.
For law, the actual History (or English) course content does not matter as long as it is intellectually rigourous and from a university where students have lots of top grades. Durham hits that. Bristol is a top one for converting to law and being successful too. However top grades are desirable but your DC will have that.
Huge applogies if I was not clear earlier.