Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
Did your father leave a Will?
Who did he leave his estate to?
But who did he want to have whatever he did have?
In that case all of your father's possessions belong to you and his former girlfriend has no right to retain them.
In fact by doing so she is committing theft.
I would suggest that you write a calm formal letter informing her that as Executors of your father's Estate you wish to take control of all his remaining possessions and that if she fails to hand them over you will report the matter to the police AND you will sue her for the return of the goods or their monetary value.
The second threat is there as to be honest it is unlikely that the police will take any action
I hope that this is of assistance please ask if you need further details