For several days in mid-February I was obsessed with a particular aspect of geometry – thickness. First it was the thickness of a slice of bread, then that of an envelope. On both occasions the critical measure was five millimetres which, in imperial units is equivalent to just under two tenths of an inch.

On the night of the 15th February we hosted a birthday dinner. In fact, it was for three birthdays; taken together, the celebrants had a total age of 218 years. Two of the guests were French and inevitably they knew something about matters culinary. Offering a mixture of French and English food seemed sensible.

With a main course, a salad, a cheese selection and a dessert to follow, the first course had to be light. Ultimately, we offered slivers of smoked fish served with bread. For the bread we borrowed an idea from the celebrated chef Auguste Escoffier who invented a ‘slimming’ dish in which he used very thinly sliced toast.  In 1897, the opera singer Dame Nellie Melba was staying at London’s Savoy Hotel and, as was often the case, she was trying to lose weight. In her honour, Escoffier, the hotel’s chef, created for her a snack using thinly cut toast. He later named the dish after her!

From my calculations, Escoffier’s Melba toast would have been around 5mm thick so we needed a bread that could stand being finely sliced. The search began weeks before the meal. Finally, we chose Chia Rye Bread – dense, moist, delicious and sold locally. By chance the baker had a state-of-the-art, rotating-steel-blade bread slicer which, by turning a dial, cuts bread at any thickness from 4 to 24mm. Initially, I was told that slices less than 7mm “Just won’t hold together”. With some persuasion, slimmer cuts were tried – at 4mm the slices collapsed; at 6mm they were too thick for our needs and at 5mm they were just as would have pleased Escoffier. And they worked! When served with fish at the birthday dinner, the 5mm ‘bread’ Melba was a success.

The episode with the envelope was less satisfactory. On every February 14 since we were married, Rohan has received two Valentine cards. Both cards are unsigned and sent by post. Of the two cards, one is classier than the other. Rohan has always suspected that both come from me and while I might hint that I could have sent the classier one, the provenance of the other remains unresolved – “How could I send something of such bad taste?”

This year the tasteful card arrived on the allotted day (the Thursday) but was unaccompanied. There was no second card again on the Friday and Rohan commented on its absence, asking if I knew what might have happened – I said nothing. Later, a note addressed to Rohan was delivered saying that a letter for her was being held at the local Royal Mail depot and would be released on payment of a supplement. I went to pay the fine and collect the errant letter.

At the counter the problem was explained – the envelope was too thick. The stamp affixed covered the price for a letter up to 5mm thick, the thickness of Rohan’s letter measured 5.5mm! It was difficult to discover exactly what could have happened but the position gradually became clearer. At the sorting office there is a modern, state-of-the-art sorting system that can process thousands of letters every minute. In next to no time it checks each envelope for its address, postcode, stamp and dimensions, then sorts it according to the street, even the house for which it is destined. Once Rohan’s letter was judged to be too thick, it was redirected by the sorting system, its advance was halted and a mechanism put in place to levy the underpaid amount and to verify that the sum was paid.

When paying the fine I was demanding. Bearing in mind its garish, rose-red colour and its date of posting, surely the envelope must have contained a Valentine card, so why was it delayed and why wasn’t the fee waived on compassionate grounds. In response a resigned face replied along the lines that “These days price cuts rule. Money now dominates how we do our business. This would not have happened before privatisation – in the old days posties could use their discretion!”

I payed the £1.50 fee and delivered the card directly to Rohan myself – by then three days late. She was pleased that once again there were two but sad to be reminded of the postal service’s penny pinching.  For me, and for personal reasons, the arrival of the second was a relief. By the way, in its hurry to levy extra income the sophisticated sorting machine forgot to frank the letter’s original stamp (see illustration).

For help with writing this blog, I would like to thank Thierry, Tom, Rebecca, Vivien and Rohan.

The illustration shows the red Valentine card envelope with a sticker requesting a fee of £1.50, a handwritten ‘5’ indicating the breached thickness, a handwritten ‘14/2’, the date of St Valentine’s Day and an unstamped postage stamp.