Considering what other processionals are earning in this country, I will say £60/hr hour is a fair rate,
Well, yes, one dictionary usage for the term "professional" is someone who is paid to do what they do. That covers 95% of the working population with the rest being volunteers, unpaid interns etc. On that basis WGs are paid considerably more than the average hourly rate and I would say that is not "fair".
Another use of the term professional is a person who has a "profession", and while a WG is colloquially a member of the "oldest profession" that's clearly not what the term means. It is meant to be used for those who can only practise in their job having met professional standards set by some external audited body. Hence the years of training and professional body membership criteria. It most definitely does not mean someone whose prerequisite for working is putting an advert on a web site and starting work that day! By the definition here charging £60/hr or £80/hr is also not "fair" by comparison. However wrong it is for those "true" professions to be able to act as a closed shop and charge high rates, there's a reason for it - supply & demand.
Which brings me to the only reason for comparing these worlds at all... "Fair" just doesn't come into it when it's a market based transaction. WGs should not try to pretend they are in any way equivalent to dentists, doctors, lawyers when it comes to their basis for charging. The sole reason for being able to charge what they charge is decided by punters and that is based on supply and demand.