As this quote begins, we find the Water Rat and Mole in Mole's old abandoned home on a cold Winter's night. Mole has been rediscovering the things he left behind while Rat has been finding something for dinner:
"At last the Rat succeeded in decoying him to the table, and had just got seriously to work with the sardine-opener when sounds were heard from the fore-court without--sounds like the scuffling of small feet in the gravel and a confused murmur of tiny voices, while broken sentences reached them--`Now, all in a line--hold the lantern up a bit, Tommy--clear your throats first--no coughing after I say one, two, three.--Where's young Bill?--Here, come on, do, we're all a-waiting----'
`What's up?' inquired the Rat, pausing in his labours.
`I think it must be the field-mice,' replied the Mole, with a touch of pride in his manner. `They go round carol-singing regularly at this time of the year. They're quite an institution in these parts. And they never pass me over--they come to Mole End last of all; and I used to give them hot drinks, and supper too sometimes, when I could afford it. It will be like old times to hear them again.'
`Let's have a look at them!' cried the Rat, jumping up and running to the door.
It was a pretty sight, and a seasonable one, that met their eyes when they flung the door open. In the fore-court, lit by the dim rays of a horn lantern, some eight or ten little fieldmice stood in a semicircle, red worsted comforters round their throats, their fore-paws thrust deep into their pockets, their feet jigging for warmth. With bright beady eyes they glanced shyly at each other, sniggering a little, sniffing and applying coat- sleeves a good deal. As the door opened, one of the elder ones that carried the lantern was just saying, `Now then, one, two, three!' and forthwith their shrill little voices uprose on the air, singing one of the old-time carols that their forefathers composed in fields that were fallow and held by frost, or when snow-bound in chimney corners, and handed down to be sung in the miry street to lamp-lit windows at Yule-time.

CAROL
Villagers all, this frosty tide,
Let your doors swing open wide,
Though wind may follow, and snow beside,
Yet draw us in by your fire to bide;
Joy shall be yours in the morning!
Here we stand in the cold and the sleet,
Blowing fingers and stamping feet,
Come from far away you to greet--
You by the fire and we in the street--
Bidding you joy in the morning!
For ere one half of the night was gone,
Sudden a star has led us on,
Raining bliss and benison--
Bliss to-morrow and more anon,
Joy for every morning!
Goodman Joseph toiled through the snow--
Saw the star o'er a stable low;
Mary she might not further go--
Welcome thatch, and litter below!
Joy was hers in the morning!
And then they heard the angels tell
`Who were the first to cry NOWELL?
Animals all, as it befell,
In the stable where they did dwell!
Joy shall be theirs in the morning!'