I don't have personal experience but I had an aquaintance who was a solicitor and he'd have sold his granny if there was a few quid in it!
Unfortunately however it's highly likely that your brother in law will need one as his wife will be very clued up financially and if the divorce is acrimonious it could get messy and expensive.
Without knowing the facts or the reasons for the split, on paper it should be straightforward and I know when it happened to my sister a lot of years ago, even though she was the "guilty party" and there were kids involved they had mediation and sorted it amicably.
If disproportionate deposits etc were involved in house purchases she'd have to prove it which she could find difficult unless their finances were always kept seperate. Even if she did, it might well be that he paid for household items, holidays etc. He may also have a strong argument that he put more manual time and labour into the estate which has added value. The pension issue is a very good point as no doubt hers will be much more valuable than his but still part of the estate.
As his wife is an accountant, he perhaps should, if they are still on speaking terms, point out how many thousands of pounds they will throw away needlessly into the hands of already overpaid and underworked solicitors.
Bob