Definition of "builder's"

He got a custard danish that had sat around too long and a cup of builder's, ate the cake while he waited on hold for the bank.

2001, Nicholas Blincoe, Matt Thorne, All Hail the New Puritans

More often it's the simple rituals of drinking that give the most pleasure: the rhythm of the morning cup of tea, whether a mug of builder's or a calming lemon-balm infusion, that helps you out of bed to start the day

2011, Victoria Moore, How To Drink, Granta Books

'Just a decent cup of builder's with milk would do me. And a biscuit or two.'

2014, Fanny Blake, With A Friend Like You, Hachette UK