Convent School Hertford 1954-1958

Sylvia, daughter of Irena (Irene) Sieradzka

I am looking for the traces of my Mum Irena (Irene) Sieradzki born in 1944. She went to St. Joseph´s Convent School in Hertford. I only have one photo of her outside the school with her father. The photo is taken in 1954.
The only thing I know is that she went to school there between 1954-58 (maybe earlier). Her father died in May 1958 and she was send to the relatives.
My Mum died last year in Reading without leaving any information about her past. I am looking for people who went to school with her, for class lists, photos, any information about the school life at that time.... whatever.
I would be grateful for any contributions.