Soon we got used to that, so when Sue Edwards asked whether I would like to engage on a project on shopping with her Year 6 at Midhurst Intermediate School I was shocked. I explained that all these themes had been eased out, that old-style primary projects were much frowned upon by them up there, that I had forgotten all my Sixties ways in the long march to respectability.

But she gave me a good lunch and set her delightful children on a charm offensive and mentioned supermarkets. In Midhurst a new one was just opening up and the old one was madly refurbishin g. It was all that people talked about, and if you want to look at change in our society, what better topic, apart from transport of course? Terrified by the thought of having to do transport, I weakly agreed to do shopping.

We started by looking at an old map of Midhurst and noticing that the main shopping street was exceptionally wide. Why? Cars not invented then, dear. Yes, horses and carts need to park, but what about other streets? Slowly it dawned on us that once North Street was a huge market area, and mustn’t it have been fun in its heyday?

The children pelted home to ask grandparents about shops in their day. Fancy buying raisins in a paper cone! Must have been horrible going to the butcher and knowing the animals were being killed round the back. And all that bloody sawdust on the floor!

We looked at Kelly’s Directories and found shops in different orders - why did they need so many boots and cabinets? We made maps of shops then and now, noting how difficult real map-making was and what huge changes had happened in my lifetime (“but he is very old”, whispered one to another).

To try to focus on this change we took a look at the world in 1938-39. A war was coming, so I made myself into a recruiting sergeant, come to Midhurst to see what he could get. I scorned the girls, who raged back at me with demands to join up, but more importantly I kept asking who would look after the shops when I marched all these people away. They thought it might be a problem.

So we set Lawrence to run a butcher’s shop, as his grandfather once did here. He had inherited loads of customers from other shops who were looked on as interlopers by his old customers. He had some very upper-class customers who felt they should be served first and who couldn’t imagine why they should moderate their demands. Above all, Lawrence was having problems with supply and with Black Marketeers who shot deer in local parks now the keepers had gone to war.

Lawrence had a tough time of it, and we all learned that supply and demand was not a simple matter. And then of course in 1945-46 when Johnny came marching back again to open up his shop there were high jinks. In this shopping business - getting and keeping customers, getting prices right, fighting off enemy traders and getting the right goods in the best condition - there were loads of problems. I know I began to look on the topic of shopping with more respect, and so did they. They had enjoyed the drama, and had gained a lot of useful knowledge.

The next stage was to look back to a distant period. I visited the West Sussex Record office and found half a dozen inventories of shop owners in Midhurst in the late 17th and early 18th century and I transcribed these with up-to-date spelling. In fact we could with some benefit have worked on the originals, but time was getting very short so I chose one, the inventory of Robert Marner of Midhurst, dated 1687. His shop was largely devoted to bedding and bed hangings and he clearly lived well on it.

We worked through the three typed pages of text, looking up difficult words in the big dictionary in the library (proving, to their great delight, that I didn’t really know what andirons were). We recreated rooms by drawing them, using histories of furniture, and finally we recreated the whole house.

I wished we had more time, for the children were beginning to realise that in the late 17th century there were very rich shops, which now we would have to go to London for. Once there was a fine provision for a rich and flourishing community.

It was close to Christmas by now - as usual I had taken a whole term and still not finished. So we hurried on to think about today. If Mrs Edwards could persuade a store manager to come in, what questions should we ask about the new supermarkets? The children set to work with a will. “How can you afford to do all these half-price things?” mused Nicola. “Do you panic?” asked Sarah. They were all keen to know about pay and prices, about freshness and competition, and some of the questions made me wonder whether a store manager dare answer them.

But when Miss Styles arrived from Somerfield s she proved well able to cope - in 50 minutes she failed to answer only two questions because she genuinely didn’t know. She told exciting stories of shoplifters, of the huge fines for having out-of-date goods on the shelves, of the horrible penalties of wastage and how much champagne costs.

The children were entranced and felt they were being let into a secret world. They now knew that shops and shopping was a very complex subject, that success in business was not that easy and next time they had to go with mum to the store they would not whine but inform. That’s what learning is all about.

John Fines is director of the Nuffield Primary History Project, published by Heinemann