That idea, that perhaps they might stay in the Past and never get back again, was anything but pleasing.

Yet no one would have dared to suggest that the charm should not be used; and though each was in its heart very frightened indeed, they would all have joined in jeering at the cowardice of any one of them who should have uttered the timid but natural suggestion, 'Don't let's!' It seemed necessary to make arrangements for being out all day, for there was no reason to suppose that the sound of the dinner-bell would be able to reach back into the Past, and it seemed unwise to excite old Nurse's curiosity when nothing they could say--not even the truth--could in any way satisfy it.

They were all very proud to think how well they had understood what the charm and the Psammead had said about Time and Space and things like that, and they were perfectly certain that it would be quite impossible to make old Nurse understand a single word of it.

So they merely asked her to let them take their dinner out into Regent's Park--and this, with the implied cold mutton and tomatoes, was readily granted.
'You can get yourselves some buns or sponge-cakes, or whatever you fancy-like,' said old Nurse, giving Cyril a shilling.

'Don't go getting jam-tarts, now--so messy at the best of times, and without forks and plates ruination to your clothes, besides your not being able to wash your hands and faces afterwards.' So Cyril took the shilling, and they all started off.