Emily Atack has announced the birth of her first child. Taking to Instagram, the Inbetweeners star posted a heartwarming snap of her cradling her newborn baby boy. Her partner and new father Alistair Garner is also featured in the picture, placing his head on Atack’s. Atack’s baby boy can be seen in a white onesie complete with an adorable hat. In the accompanying caption, Atack revealed what she and Garner had decided to call their son, admitting her “dreams have come true”. She penned to her 1.9million Instagram followers: “We have a beautiful son. Barney James Garner. All my dreams have com…