The custody battle, over two sons taken by their father to Russia, will be taken to a Moscow court of appeal next Thursday.
Mother Rachael Neustadt said she would be “flying straight there” from her home in Hendon after hearing the news last week.
“I’m so happy. We have so much documentation and hope this goes in our favour,” she said.
Daniel and Jonathan, seven and five, were taken to Moscow by their father Ilya last December. Ms Neustadt thought they were going on a two-week holiday.