According to the London Evening Standard, Cosmo restaurant in Croydon — which, until now, was mostly known for being the largest restaurant in England — is charging customers £3 (US$4.67) per baby. Even when they're young enough to sit on their mothers' laps the whole time! Cosmo doesn't have room to spare in their "800-seat, 22,000 sqft oriental buffet restaurant" for infants who aren't ponying up for egg rolls.
It appears to be their standard policy: adults are charged one fee, children "under 150cm" another, with a £3 minimum fee. Hence, infant admittance is £3.