Then there was fat little Mrs. Jolly from the sweet-shop, kindness itself. No, it couldn’t possibly be her! Why, every one loved her, and she was exactly like her name. She was kind and generous to everyone, and she nodded and smiled at Daisy as she caught her eye. Daisy was certain that before the trip was ended she would be handing sweets out to all the children!

Well, that was three out of the five passengers! That only left two possible ones. One was a thin, dark, sour-faced man, huddled up over a newspaper, with a pasty complexion, and a curious habit of twitching his nose like a rabbit every now and again.

This fascinated Bets, who kept watching him. The other possible person was a young girl about eighteen, carrying sketching things. She had a sweet, open face, and very pretty curly hair. Daisy felt absolutely certain that she knew nothing whatever about the letters.

‘It must be that sour-faced man with the twitching nose,’ said Daisy to herself. She had nothing much to do because it was no use tackling Mr. Goon and talking to him. It was plain that he could not be the writer of the letters. So she watched the others getting to work, and listened with much interest, though the rattling of the bus made her miss a little of the conversation.

‘Good morning, Miss Trimble,’ Daisy heard Larry say politely. ‘I haven’t seen you for some time. Are you going to the market too? We thought we’d like to go today.’

‘Oh, it’s a pretty sight,’ said Miss Trimble, setting her glasses firmly on her nose. They were always falling off, for they were pince-nez, with no side-pieces to hold them behind her ears. Bets loved to count how many times they fell off. What with watching the man with the twitching nose and Miss Trimble’s glasses, Bets quite forgot to talk to Mrs. Jolly, who was taking up most of the seat she and Bets was sitting on.

‘Have you often been to Sheepsale market?’ asked Larry.

‘No, not very often,’ said Miss Trimble. ‘How is your dear mother, Laurence?’

‘She’s quite well,’ said Larry. ‘Er - how is your mother, Miss Tremble? I remember seeing her once next door.’

‘Ah, my dear mother isn’t too well,’ said Miss Trimble. ‘And if you don’t mind, Laurence dear, my name is Trimble, not Tremble. I think I have told you that before.’

‘Sorry. I keep forgetting,’ said Larry. ‘Er - does your mother live at Sheepsale, Miss Trem - er Trimble? Do you often go and see her?’

‘She lives just outside Sheepsale,’ said Miss Trimble, pleased at Larry’s interest in her mother. ‘Dear Lady Candling lets me go every Monday to see her, you know - such a help. I do all the old lady’s shopping for the week then.’

‘Do you always catch this bus?’ asked Larry, wondering if by any conceivable chance Miss Trimble could be the wicked letter-writer.

‘If I can,’ said Miss Trimble. ‘The next one is not till after lunch you know.’

Larry turned and winked at Fatty. He didn’t think that Miss Trimble was the guilty person, but at any rate she must be put down as a suspect. But her next words made him change his mind completely.

‘It was such a nuisance,’ said Miss Trimble. ‘I lost the bus last week, and wasted half my day!’

Well! That put Miss Trimble right out of the question, because certainly the letter-writer had posted the letter to poor Gladys the Monday before - and if Miss Trimble had missed the bus, she couldn’t have been in Sheepsale at the right time for posting!

Larry decided that he couldn’t get any more out of Miss Trimble that would be any use and looked out of the window. Bets seemed to be getting on well with Mrs. Jolly now. He couldn’t hear what she was saying, but he could see that she was busy chattering.

Bets was getting on like a house on fire! Mrs. Jolly greeted her warmly and asked after her mother and father, and how the garden was, and had they still got that kitchen cat that was such a good hunter. And Bets answered all her questions, keeping an interested eye on Miss Trimble’s glasses, which had already fallen off twice, and on the sour-faced man’s twitching nose.

It was not until she saw how earnestly Fatty was trying to make the sour-faced man talk to him that she suddenly realized that she too ought to find out a few things from Mrs. Jolly. Whether, for instance, she always caught this bus!

‘Are you going to the market, Mrs. Jolly?’ she asked.

‘Yes, that I am!’ said Mrs. Jolly. ‘I always buy my butter and eggs from my sister there. You should go to her stall too, Miss Bets, and tell her you know me. She’ll give you over-weight in butter then and maybe a brown egg for yourself!’

‘She sounds awfully kind - just like you’ said Bets.

Mrs. Jolly was pleased and laughed her hearty laugh. ‘Oh, you’ve got a soft tongue, haven’t you?’ she said. Bets was surprised. She thought all tongues must surely be soft.

She looked at Mrs. Jolly, and decided not to ask her any more questions about going to Sheepsale every Monday because nobody, nobody with such kind eyes, such a lovely smile, such a nice apple-cheeked face could possibly write an unkind letter! Bets felt absolutely certain of it. Mrs. Jolly began to fumble in her bag.

‘Now where did I put those humbugs?’ she said. ‘Ah, here they are? Do you like humbugs, Miss Bets? Well, you help yourself, and we’ll pass them over to the others as well.’

Pip was sitting by the young girl. He found it easy to talk to her.

‘What are you going to paint?’ he asked.

‘I’m painting Sheepsale market,’ she answered. ‘I go every Monday. It’s such a jolly market - small and friendly and very picturesque, set on the top of the hill, with that lovely country all round. I love it.’

‘Do you always catch the same bus?’ asked Pip.

‘I have to,’ she said. ‘The market’s in the morning, you know. I know it by heart now - where the hens and ducks are, and the sheep, and the butter-stalls and the eggs and everything!’

‘I bet you don’t know where the post-office is!’ said Pip quickly.

The girl laughed and thought. ‘Well, no, I don’t!’ she said. ‘I’ve never had to go there and so I’ve never noticed. But if you want it, any one would tell you. There can’t be much of a post-office at Sheepsale, though. It’s only a small place. Just a market really.’

Pip felt pleased. If this girl didn’t know where the post-office was, she could never have posted a letter there. Good. That ruled her out. Pip felt very clever. Anyway, he was certain that such a nice girl wouldn’t write horrid letters.

He looked round at the others, feeling that his task was done. He felt sorry for Daisy, sitting next to the surly Mr. Goon. He wondered how Fatty was getting on.

He wasn’t getting on at all well! Poor Fatty - he had chosen a very difficult passenger to talk to.

The sour-faced man appeared to be very deep indeed in his paper, which seemed to Fatty to be all about horses and dogs.

Buster sniffed at the man’s ankles and didn’t seem to like the smell of them at all. He gave a disgusted snort and strained away towards where Mr. Goon sat, a few seats in front.

‘Er - I hope my dog doesn’t worry you, sir,’ said Fatty.

The man took no notice. ‘Must be deaf,’ thought Fatty and raised his voice considerably. ‘I hope my DOG doesn’t WORRY you, sir,’ he said. The man looked up and scowled.

‘Don’t shout at me. I’m not deaf,’ he said. Fatty didn’t like to ask again if Buster worried him. He cast about for something interesting to say.

‘Er - horses and dogs are very interesting, aren’t they?’ he said. The man took no notice. Fatty debated whether to raise his voice or not. He decided not.

‘I said, horses and dogs are very interesting, aren’t they?’ he repeated.

‘Depends,’ said the man, and went on reading. That wasn’t much help in a conversation, Fatty thought gloomily. The others were jolly lucky to have got such easy people to tackle. But still - of all the passengers in the bus, this man looked by far the most likely to be the letter-writer - sour-faced, scowling, cruel-mouthed! Fatty racked his brains and tried again.