The empty café table

Text 1: Half Past Ten, by Colin Ashdown

An original short story extract.

For three years Mr Halloran had come into the Bluebell Café at half past ten. He sat at the table by the radiator, ordered a pot of tea and a toasted teacake, and did the crossword in pencil, always finishing before eleven. Dora had his order on the counter before he reached his chair. Today the clock above the coffee machine said ten forty, and the table by the radiator was empty. Dora wiped it anyway. She wiped it again at ten fifty. Every time the bell over the door jangled, she looked up, and every time it was someone else: two builders, a woman with a pushchair, a boy wanting change for the bus. At eleven she poured the tea she had made for him down the sink. Then she took off her apron and asked Sam to mind the till.

Explain why Dora looks up every time the bell over the door rings.