Why? Sheila wasn't materialistic. Her needs were emotional. Financially, she was catered for. I'll bet the purse strings were never tightened when it came to her needs because of the boys and their needs.
Oh, c'mon, I took you to be more intelligent than you appear to be.
Sheila had been materialistic. Why a property in Maida Vale ? Wasn't a cottage in the same village as her family good enough ?
It seems that while living with Colin she wanted her own way or threw a strop along with pots and pans.
In her younger life her parents bent over backwards to find her and fund her the job which she wanted and even that didn't seem enough. Parents funded her trip to Japan which was a waste of time and money. In the end Sheila didn't have to work. Wouldn't we all have loved such a life ?