Thanks for your question
Potentially yes there is Inheritance tax due and possibly capital gains as
1) Andrew gifted the property to Jon yet continued to live in the property and benefit from it - doesnt appear to have paid any rent to Jon
2) When did Jon then gift the property to Julia and Andrew ? Did he pay capital gains tax as he was gifting a property that was not his main residence
3) Does Toby still live in this property with his family and does Julia also live here
4) What does Julia wish to do re the property in her will?
I can then advsie further