He was obviously very pleased with his look. And mid-grey was a good choice of odd jacket to go with the blue jeans. The tie was new, and the white shirt was clean and crisp.

But somehow it didn’t work as a casual outfit, not with the jeans and suede shoes.

Can you guess why this outfit didn’t really come off? Let me give you a clue. The jacket was worsted, part of a suit. The tie was silk.

It was, as a friend immediately christened it, the newsreader look: all smart, buttoned-up business on top, casual and relaxed below. (The name of the look referred to the urban myth that all newsreaders wear jeans and trainers below the desk, where the audience can’t see them.)

The contrast between this smart outfit on top and casual below was just too strong. And it was all a question of the materials.

The smooth wool of a suit jacket rarely looks good with jeans. The tie was smooth and silk, obviously fitting well with the jacket but not with the jeans. And the shirt was also wrong – although this was more a question of colour and type (white, Windsor collar with double cuffs).

Each of these pieces on top would have worked better if they had been a more casual version of themselves. The jacket could remain grey, but be made of a rougher material such as flannel, camelhair or linen. The tie could be woollen, or knitted silk, but either way have a surface more akin to the jeans and suede shoes. And the shirt would have been more casual if it was blue, if it had a buttoned-down collar, if it had single cuffs or indeed if it was a rougher cotton, such as an Oxford.

All of these changes in the materials would have made the top half fit with the bottom half.

The outfit didn’t need all of these changes necessarily. Silk ties can work very well with more casual trousers, often if they are lighter in weight or a more casual colour. White shirts can also work well with casual jeans, even if they have more formal collar and cuffs.

But the outfit needed something, it needed one of these things to change. Otherwise it seemed disjointed.

The problem is that men find shifting formal clothes into a casual outfit difficult. They find it so because they concentrate on the colours, or on an established formal combinations that they know works.

To them I say – concentrate on the materials, on how rough or smooth they are. After that you can’t go too far wrong.