I can't be sure how the nippers felt. In years to come, in grown-up reminiscences about the childhood holidays, will they roll their eyes and groan? Will they rue things they could have done? The funfairs not visited, the go-karts not ridden, the sombreros not worn?

I hope they will laugh about the time Dad took them to a wind-blown beach just north of Felixstowe on a week-long letter box hunt. I hope they will learn to love the history of the commonplace and the aesthetics of the familiar. Perhaps they would have preferred Disneyland. But they ain't going to get it. Not with this Dad.

I won't forget my own introduction to these red-breasted beauties. It was a “VR”, wall-mounted and half hidden in a hedgerow on the North Downs. I was struck immediately. It was, for me, a magical little window opening on to the sepia-tinted world of Queen Victoria.

Who were the people who used the box? What did they wear and what did they do for a living? Did they walk here or, like me, ride? While I was on my new bike, they, surely, would have had a horse? Were they parsons or milkmaids, tax inspectors or apothecaries? What did they write about and who did they write to? Did they find the box strikingly pretty or boringly functional? How could they fail to be amazed, as I was, at the simple ingenuity and efficient co-ordination required to collect, sort, send and deliver their words of wisdom, their bills, and their sweet nothings?

The posties' guide to Britain

Royal Mail's finest divulge the hidden gems of their post rounds, from central London to rural Cornwall

• London tours - by water

Five perfect minibreaks in Britain

Boutique bolt holes, meadowy picnics, wild walk - the best of both worlds on small-town weekenders

• 12 great madcap British weekends

12 great madcap British weekends

The range of summer activities Britain boasts is inspired, and occasionally baffling - here's the pick

Britain's best 50 days out

Going abroad this summer? It’ll be very nice and everything, but here's what you’re missing

• Britain's best 25 family days out

Related Links

• The posties' guide to Britain

Thanks to this brightly coloured cast-iron box, I have enjoyed a life-long love of history. OK, it is not the kind of knowledge that is going to win me any awards or bring down the Government. But it's interesting, amusing and mostly innocent. (I do recall having to stifle a pre-pubescent giggle when the meaning of the bold VR insignia was explained to me. Kings, I was told, were always Rex. Queens, meanwhile, had Reginas.)

Postbox hunters can end up in some tawdry suburbs. I have found myself skulking around some of our nastier 1930s housing estates hoping to spot an ultra-rare Edward VIII. Why? There's the thrill of the chase, of course. But it's the associations as well. Whose hearts strings could not be plucked by the desperately romantic story of how a king sacrificed his throne for the love of an American divorcée? Track one of them down. Then cock your head to one side and you, like me, might see a W for Wallis Simpson rather than a curly E for Edward the Eighth.

There are about ten main types of letter box: they come in pillar, wall and post-mounted forms. There are about 300 discrete types, once you tot up the large number of modifications. It took them ages to design a rain-waterproof aperture. Then the size of letter got bigger and the slots had to be widened in response. Attentive spotters will relish the markings of the Handyside foundry, Derby, or of Glasgow's McDowell Steven works. Others might think this was just going too far.

Of the 116,000 boxes dotted up and down the country, no more than a couple of hundred date from the ten-month reign of the king who lost his crown to love. About 6 per cent are Victorian, with a similar number dating from the 1901 to 1910 reign of Edward VII.

About 55 per cent carry the EIIR cipher of our current Queen. Boxes bearing the wonderfully curvaceous cipher of the Queen's father account for another 11 per cent. And those 23 per cent of boxes dating from the reign of her grandfather raise an intriguing, and blissfully unimportant, secret.

Why does the GR cipher bear no roman numeral V? You might think it was because George V was the first “G” in postbox history and did not need the distinction. But in that case Edward VII boxes would have no VII. And they do.

The children (girl, 10, girl, 8, boy, 5) seemed content to spend a week's holiday indulging me and my silly little hobby. They took it in turns to note down the vital statistics of all 90 letter boxes we passed, and by the end of the week they were discussing the relative merits of the G6 and the VR with interest that verged on enthusiasm. Fortunately for them, there is more to the Suffolk coast than red letter box boxes.

The walking can be blowy and is untroubled by anything as challenging as a hill. But flatlands are good too. Above is the widest of open skies and below, it brims with history of both the natural and military varieties. Minsmere, the reserve run by the Royal Society for the Protection of Birds, is a magnet for twitchers on the lookout for whimbrel, garganey and a thousand other rare and not so rare breeds.

Times recommends

• The Green Spaces Travel Awards, 2008 - the winners
• Britain's 12 best winter walks
• The insiders' guide to bohemian Paris