I like the idea Mycroft left Irene’s phone on purpose in her file when he handled it to John.
Perhaps he knew Sherlock wanted to keep a reminder of her. Perhaps he knew how much Sherlock cared about Irene even if Sherlock didn’t tell anything.
I know Mycroft didn’t want to hurt his little brother by telling him the truth. She’s dead and he won’t be able to see her anymore.
So he let Sherlock have the phone so he can still read her texts. After, Mycroft didn’t erase that memory from the phone.
Once again, we can see Mycroft cares his little brother despite everything. He knows Irene was precious and he let him have that item.
Also, I like to think Mycroft didn’t remove that reminder of Irene from Sherlock’s flat. Even if the phone belongs to England now, he let it go.
It was a present for his little brother. It was something precious.










