‘We’re just where we were! ’ said Fatty gloomily. ‘Sickening, isn’t it? I don’t think we’re such good detectives as we hoped we were! You go off to the market. I want to have a good think. I may get a much better idea soon!’

So off to Sheepsale market went the others, leaving poor Fatty behind, looking extremely gloomy.

The children had a really lovely time at the market. They loved every minute of it. It was such a noisy, lively, friendly place, the birds and animals were so excited, the market-folk so good-humoured and talkative.

They found Mrs. Jolly’s sister, and she insisted on giving each of them a large brown egg, and a small pat of her golden home-made butter for their breakfast. Bets was simply delighted. She alway loved an unexpected present more than any other.

‘Oh thank you!’ she said. ‘You are kind - just exactly like Mrs. Jolly. She gives us sweets. Is your name Jolly, too?’

‘No. I’m Mrs. Bunn,’ said Mrs. Jolly’s sister and Bets very nearly said, ‘Oh, that’s just the right name for you!’ but stopped herself in time. For Mrs. Bunn was exactly like her name - big and round, and soft and warm, with eyes like black-currants.

‘Let’s go and find Fatty and tell him to come and see the market,’ said Bets. ‘I don’t like to think of him glooming by himself. We’re stuck over this case, and I don’t believe even Fatty can unstick us.’

‘There’s the artist girl, look!’ said Pip. And there she was, in the middle of the market, painting hard, gazing at all the animals and birds around her in delight. The children went and looked at her picture and thought it was very good indeed.

Bets went to find Fatty. He was sitting on a bench in the village street, lost in thought. Bets looked at him in admiration. She could quite well imagine him grown-up, solving deep mysteries that nobody else could. She went up to him and made him jump.

‘Oh, Fatty, sorry! Did I make you jump? Do come and see the market. It’s marvellous.’

‘I haven’t quite finished my pondering yet,’ said Fatty. ‘Perhaps if I talk to you, Bets, I might see things a little more clearly.’

Bets was thrilled and proud. ‘Oh yes, do talk to me, Fatty. I’ll listen and not say a word.’

‘Oh, you can talk too,’ said Fatty. ‘You’re a very sensible little person, I think. I haven’t forgotten how you guessed that telegraph-boy was me, just because you happened to see Buster staring up at me adoringly.’

Buster looked up at the mention of his name. He was looking gloomy, because he was still on the lead. He badly wanted to go off to the market, because the smells that came from it were too exciting for words. He wagged his tail feebly.

‘Buster looks as if he’s pondering too,’ said Bets. Fatty took no notice. He was looking off into the distance, deep in thought. Bets decided not to disturb him. He could talk to her when he wanted to. She began to practise twitching her nose just as she had seen the sour-faced man do. Buster watched her.

Fatty suddenly noticed it too and stared. ‘Whatever’s the matter with your nose?’ he said.

‘I’m only just twitching it like that man did,’ said Bets. ‘Talk to me, Fatty.’

‘Well, I’m trying to work out what’s best to do next,’ said Fatty. ‘Now - every Monday for some weeks past somebody has posted a letter to catch the 11.45 post here in Sheepsale - and each of those letters has gone to people in Peterswood. Well, if you remember, I said that that looked as if somebody living in Peterswood, who knew those people and possibly their histories, must have posted them.’

‘Yes, that’s right,’ said Bets.

‘And we worked out that the letter-writer probably caught that bus on a Monday and posted the letter on getting out,’ said Fatty. ‘So we caught the same bus, but we haven’t found any one we could really suspect - though mind you every one of those bus passengers must go down on our list of Suspects - and we didn’t catch anyone posting a letter either.’

‘You’re not going to put Clear-Orf or the vicar down on the list, are you?’ said Bets, astonished.

‘Every single person is being put there,’ said Fatty firmly. ‘We can easily cross them out if we think we should - but they’ve all got to go down.’

‘I dare say Clear-Orf has put us all down on his list of Suspects too then,’ said Bets unexpectedly. ‘I expect he was on that bus for the same reason as we were - to have a look at the passengers and watch who posted a letter.’

Fatty stared at Bets. Then he burst out into such a hearty laugh that Bets was startled. ‘Have I said something funny?’ she asked.

‘No, Bets. But don’t you realize which of the passengers posted a letter?’ said Fatty, grinning.

‘Nobody did,’ said Bets. ‘Well - except you, of course!’

‘Yes - me!’ said Fatty. ‘And it’s going to make old Goon scratch his head hard when he thinks that of all his precious Suspects only one posted a letter - and that was his pet aversion, Frederick Trotteville!’

Bets laughed too. ‘That’s funny!’ she said. ‘But, Fatty, nobody could possibly think you would write horrid letters like that!’

‘Old Clear-Orf would believe I’d stolen the Crown Jewels, if there was any suspicion of it,’ said Fatty. ‘He’s got such a bad opinion of me! He’d think me capable of anything. Golly - he must be in a state, wondering who’s going to get that letter tomorrow morning!’

‘And nobody will get a letter!’ said Bets. ‘Because one hasn’t been posted. It will be the first Monday that is missed for six weeks. I wonder why?’

‘So do I,’ said Fatty. ‘Of course - if one does arrive - it will mean that the writer lives in Sheepsale after all, and has just posted the letter any time this morning, before the bus came up. Then we shall be properly stuck. We can’t watch all the inhabitants of Sheepsale posting letters!’

‘Perhaps whoever comes up on the bus to post the letters each Monday didn’t come today for some reason,’ said Bets.

‘That’s an idea,’ said Fatty. ‘When we go back on the bus we’ll ask the conductor if he always has his regular passengers each Monday, and see if any didn’t go this morning. We could make inquiries about them too - see if they’ve got any spite against Gladys or Molly or the others, and so on.’

‘When’s the next bus back?’ asked Bets. ‘I wish we could stay here for the day, Fatty. You’d love the market. But we haven’t got our lunch with us.’

‘We could have it in that little shop over there,’ said Fatty, pointing. ‘Look - it says, ‘Light Lunches.’ That probably means eggs and bread, and butter and cake. How would you like that?’

‘Oh, it would be lovely,’ said Bets. ‘You do have good ideas, Fatty. But Mother would be anxious if we didn’t come back.’

‘I’ll do a spot of phoning,’ said Fatty, who never minded doing things of that sort. Bets thought how like a grown-up he was, always deciding things, and, what was more, always seeming to have plenty of money to pay for everything!

Fatty disappeared into the post-office and went into the telephone box. He made three calls very quickly and came out.

‘It’s all right,’ he said. ‘I phoned up your mother and Larry’s mother and mine - and they all said, “Good riddance to you for the day!” ’

‘They didn’t, Fatty!’ said Bets, who simply couldn’t imagine her mother saying any such thing.

‘Well - not exactly those words,’ grinned Fatty. ‘But I could tell they weren’t sorry to be rid of us for the day. I don’t think my mother, for instance, liked that new game of ours very much.’

‘I shouldn’t think she did, really,’ said Bets, remembering the yowling and groaning and rolling over and over that went with Fatty’s new game.

‘Let’s go and tell the others we can stay here for lunch. Won’t they be thrilled!’

They were. ‘Good old Fatty!’ said Larry. ‘It’s a treat to be up here on a day like this, among all the farming folk and their creatures. What’s the time? I’m getting jolly hungry.’