Thank you for responses. I contacted Middlesbrough diocese and asked about the Admission records for Crossbeck convent. The response was "In terms of our records, I want to clarify the status of the collections we hold. The North Ormesby collection is unfortunately closed to public access until 2037 due to restrictions in place as a private archive. As for the Crossbeck House collection, it is accessible, but I must let you know that it does not contain the specific details you’re searching for. This collection primarily documents major events, like professions and annual celebrations, rather than everyday visitors or personal encounters". I am almost certain that my nan was there. She died in 1969, so I find it hard to understand why there is no public access for another 13 years !!! It will be too late for my own mum ( who is 90 years old), to know if her mother was there & I certainly will be far too old to even remember I had made such an enquiry !!!
Is this where my research now comes to an end?