a glass of milk and a bun

If Henry hadn't been determined to quarrel he would have taken her out to lunch first, and now she would have to go and have a glass of milk and a bun in a creamery with a lot of other women who were having buns and milk, or Bovril, or milk with a dash of coffee, or a nice cup of tea. It was a most frightfully depressing thought, because one bun was going to make very little impression on her hunger, and she certainly couldn't afford any more.

Patricia Wentworth

The Case is Closed (1937)

Not my favourite Wentworth - that is perhaps

 The Case of William Smith or Lonesome Road?

she always felt cheerier at breakfast

'How can you eat that sawdust, Father?' she inquired, beginning on eggs and bacon and speaking cheerfully because it was a fine morning and only ten minutes past nine; and somehow, at the beginning of every new day, there was always a chance that this one might be different from all the rest. Something might happen; and then everything would be jollier all round.

Madge did not see clearly into her feelings; she only knew that she always felt cheerier at breakfast than at tea.

...

'What time did you say Viola's train gets in?' Tina asked her mother; she sometimes found the Wither silences unendurable.

'Half-past twelve, dear.'

'Just in nice time for lunch.'

'Yes.'

'You know perfectly well that Viola's train gets in at half-past twelve,' intoned Mr Wither slowly, raising his eyelids to look at Tina, 'so why ask your mother? You talk for the sake of talking, it's a silly habit.' He slowly looked down again at his little bowl of mushy cereal.

'I'd forgotten,' said Tina. She continued vivaciously, at the silence. 'Don't you loathe getting to a place before twelve o'clock, Madge – too late for breakfast and too early for lunch?'

Stella Gibbons

Nightingale Wood (1938)

diluting the milk

He didn't know – he couldn't possibly have known – that in spite of all her economies, in spite of stinting and scraping, of eschewing meat, and eating margarine instead of butter, and diluting the milk, and buying the very cheapest tea that floated like dust on the top of your cup, Miss Buncle's account at the bank was overdrawn by seven pounds fifteen shillings and would soon have been overdrawn by more; for the dividends, which had been steadily decreasing, had now practically ceased. There were tears in Miss Buncle's eyes as she signed the receipt and folded up the amazing note. Fancy that tiny piece of paper representing so much! It really was rather astonishing (when you come to think of it) what that tiny piece of paper represented – far more than a hundred sovereigns (although in modern finance less). It represented food and drink to Barbara Buncle, and, perhaps, a new winter coat and hat; but, above all, freedom from that awful nightmare of worry, and sleep, and a quiet mind.

D. E. Stevenson

Miss Buncle's Book (1934)

Some thoughts here.