I am an unmarried mother with two children, who each have a different father.
DS1 is Sailor-Smith and DS2 is Sailor-Bloggs.
I am neither chavy or pretentious. I wanted my children to have my name as I was unmarried and, should anything happen, I would become the primary carer and the hassle of having a different surname would become an inconvenience (passports and travel etc).
Although my circumstances with DS2 are completely different to DS1 (living together in own home, committed vs young and in an emotionally abusive relationship) I still wouldn't risk it. It also made my DS1 feel connected to DS2 as they had, somewhat, the same name.
My DS1 already goes by only my surname, and despite registering him as Sailor-Smith in school he turned around a few weeks in and only wanted to be known as Bob Sailor. The teachers spoke to me and respected his wishes.
If DS2 only wants to be known as Bloggs then so be it.
My children will have multiple options on getting married and having children themselves.