sonia pereiro-mendez says she was denied millions in pay and bonuses when she announced she was expecting her first child .
male colleagues at the bank were promoted ahead of her and she was ` mocked ' and subjected to ` gratuitous derogatory ' comments about her childcare arrangements , she alleges .
so in an attempt to prove her claim , she recorded managers at the global investment firm ` without their knowledge ' , a tribunal heard yesterday .