From The Missing Partners, by Henry Wade:

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One of the ship's firms, the S.S. Snark, was due to sail next day.

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"Just some routine questions he was asking."

"Routine gradmothers!"

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"I might faint and then you ought to be present and apply 'restoratives'--whatever they are."

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[A cameo from a cartoon character, to punctuate an emotional moment! The characters are conversing intimately between features at the cinema...]

"It simply is that I'm not capable of loving anyone as you do--not at present, at any rate--I may be some day."

She gave his hand a little pat and released her own. Felix strode into view, turned and strode back, frowning....

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[From the final paragraph of the book!]

So it was that he set foot upon the S.S. Pedantic full of hope for the future.

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[Bonuses: (1) a reference to an incidental offstage character called Honourable Gweneth Bootle]; (2) a (presumably fictitious) stage show called Happy Hopscotch.