"If this father had willed the house to the widow, could the son have challenged the will for failure to make adequate provision, do you think? (Assuming he was still in full-time education, for example) "
Goodness me, this has certainly sparked something off!
By way of background, it is helpful to note that the Succession Act brought in provision for widows/widowers who might otherwise not have been provided for by their spouses. The classic example was where a farmer left the farm to the eldest son.
So the Succession Act says that, if you married and are making a will, you must make provision for a spouse ( where no children) of not less than 50% of sole assets - (because joint assets will pass automatically outside the net estate). If there are children, the spouse is entitled to not less than 33%.
And if there is no will, the Succession Act says that the spouse gets 66% and the children share the remaining 33%. And then there are various helpful sections about appropriating the family home.
In (very) broad terms, the norm is for spouses to leave all of their estate to their spouses with the children only inheriting if the surviving parent is widowed before death. So, in the question posed - could the son have challenged the will?- the answer is yes, he could challenge but the more important issue is whether a Court would hear him and make any order in his favour. The High Court generally takes the view that provision for spouses is the priority.
I hope that helps a little and that anyone ( married with children) reading this would consider making a will as a priority. It can save a lot of heartache.
mf