At this point I shall once more mention my uncle Jack. He was Dad's sister's husband. When he died, my mum, who had known him all her married life, was astonished to learn that his name was actually Horace.
Peggy is a diminutive of Margaret.
Here is a useful list of variants of Mary, which I got from....... somewhere:
Mary has 102 variant forms: Mair, Mal, Malia, Mallie, Mame, Mamie, Manette, Manon, Manya, Mara, Marabel, Marabelle, Mare, Maree, Marella, Marelle, Maren, Maretta, Marette, Maria, Mariam, Marian, Mariana, Mariann, Marianna, Marianne, Marice, Maridel, Marie, Mariel, Mariela, Mariella, Marielle, Marietta, Mariette, Marilee, Marilin, Marilla, Marilyn, Marin, Marion, Mariquilla, Mariquita, Mariska, Marita, Maritsa, Maritza, Marja, Marjan, Marje, Marla, Marlo, Marya, Maryann, Maryanne, Marybel, Marybell, Marybeth, Maryjo, Marylee, Marylin, Marylou, Marylu, Marysa, Maryse, Marysia, Masha, Maura, Maure, Maureen, Maurene, Maurine, Maurise, Maurita, Maurizia, Mavra, May, Mayme, Maymie, Mayra, Mayria, Meridel, Meriel, Mimi, Minette, Minnie, Minny, Miriam, Mitzi, Moira, Moire, Moll, Mollie, Molly, Morag, Moya, Muire, Murial, Muriel, Murielle, Poll and Polly.
But then my dad sometimes called my mother 'Polly', and her name was Vera