In spite of the horror shown by many on here...the law is behind the mother.....sorry
From wiki....
United Kingdom
Breastfeeding in public (restaurants, cafes, libraries etc.) is protected under the Sex Discrimination Act 1975 under the provision of goods, facilities and services section. If the child is under six months old, the mother has additional protection under a 2008 amendment to the act which protects maternity rights. This is superseded by the Equality Act 2010 which clarifies that a business must not discriminate against a woman who is breastfeeding a child of any age in a public place.[26][27] Her companion(s) are also protected by this act.
A 2004 UK Department of Health survey found that 84% (about five out of six people) find breastfeeding in public acceptable if done discreetly; however, 67% (two out of three) of mothers were worried about general opinion being against public breastfeeding.[28] To combat these fears in Scotland, the Scottish Parliament passed legislation safeguarding the freedom of women to breastfeed in public in 2005.[29] The legislation allows for fines of up to £2500 for preventing breastfeeding of a child up to the age of two years old in public places,[30][31]