My instant though on 'non girly' was to go to the popular American type names (which I love btw, I'm not sneering at them). But there are also lots of more English sounding ones. I agree with whoever said avoid a and y endings for the most part, though there are some shorter names with a endings which still don't sound girly to me.
British/Irish tradition (sorry for any repeats):
Amber, Autumn, April, Aisling, Bethan, Bridget, Bronwen, Carys, Cerys, Constance, Cara, Cora, Claire, Dana, Diane, Emma, Erin, Edith, Eve, Ellen, Evelyn, Esther, Ffion, Faith, Frankie, Frances, Gemma, Georgia, Hannah, Hero, Hope, Iris, Judith, Joanne, Karen, Kiran, Kate, Katelyn, Kathryn, Lauren, Lois, Leah, Megan, Meredith, Morvern, Merryn, Miriam, Nicole, Nadine, Olive, Pearl, Quinn, Ruth, Rachel, Rhian, Robyn, Rowan, Seren, Stella, Shannon, Sian, Siobhan, Sinead, Tara, Tess, Tamsin, Yasmin
American/Modern style:
Ashlynn, Addison, Adelyn, Avery, Brooke, Brooklynn, Brogan, Brynn, Briley, Bailey, Cassidy, Cadence, Camryn, Carmen, Delaney, Dylan, Emerson, Eden, Emery, Ellis, Farron, Genesis, Hadley, Hayden, Harper, Jordan, Jayden, Kinsley, Kendall, London, Morgan, Macey, Marley, Madison, Paige, Peyton, Payson, Piper, Riley, Reese, Reagan, River, Sutton, Spencer, Sydney, Taylor