What do you call a suit without a tie?

If you're a man it doesn't really matter how you feel about ties. There are some occasions when you'd be foolish not to wear one. If I were being asked to appear before a select committee, for instance, I would wear a tie.

Matt Brittin, the CEO of Google UK, didn't feel he needed to when he turned up yesterday to talk about his company's tax arrangements. It seemed to say a lot about how seriously his company takes Parliament.

Tim Davie also went for the open-necked shirt in his first day as acting Director General of the BBC. When he gave his interview down the line to Sky News it gave an impression of informality which was at odds with the formal meetings he was having with colleagues. This can't have been what he wanted. (People who work in TV should surely know better than anyone that when you're on camera viewers are getting most of their signals from what you look like rather than what you say.)

Both these men work in companies where even the senior management go tieless nowadays. Maybe they should dress differently when representing those organisations in the outside world. The "one of the guys" look may work OK if you're squeezing into the lift in the morning, clutching a cup of coffee. When you're facing the music it can easily look disrespectful.

We seem to have a generation of  male executives who think it doesn't matter. They ought to ask their female colleagues. No woman would have dreamed of appearing in front of parliament or the media in anything other than her best armour.

When George Entwistle got the job of Director General of the BBC Alastair Campbell congratulated him and said "get yourself some decent suits". There was nothing particularly wrong with Entiwistle's suits but maybe Campbell  detected that he didn't wear them seriously enough.

The wearing of a proper suit in the so-called "creative industries" indicates many things, one of them being that you are prepared to be a hardass. The subliminal message is "I no longer care particularly whether you like me or not - I will do what I think is right."

Some managers make the mistake of thinking that the staff will like them more if they appear to be dressing like them. They don't. Particularly in the creative industries staff prefer to think that the management is not like them. They like to think they're grown-ups. They like to think somebody else is steering the ship while they're having all kinds of fun below decks. Martin Scorsese hasn't made a memorable film in years but his personal stock remains high because every time he appears in public he looks as if he's about to walk his daughter down the aisle.

When people are sent to see a male specialist they want somebody who looks like a headmaster from the 1960s and not somebody who might be running a copy shop.  Even those authority figures who don't bother with suits appreciate the important of looking as if they've thought about their uniform. Steve Jobs didn't wear a black turtle neck because it was the nearest thing to hand when he got up in the morning. It was part of his identity. With his thin and no doubt expensive sweaters Simon Cowell has proved that it's possible to make a uniform out of anything.

The suit without tie get-up looks like the wearer hasn't got the courage of his convictions. He's trying to look "smart" without looking smart. He's trying not to look like a grown-up. Paul Du Noyer says too many men today dress "like toddlers". You can see what he means in the supermarket queue. Baggy sweat shirts, hoodies, the kind of footwear that inspired Ian Dury to talk about "shoes like dead pig's noses". It's as if they want to crawl back into mother's arms and go to sleep.

The point in men's lives when they have to grow up has receded over the years. It's no longer strictly 21 or 30 or even 40. When you're a father the signal arrives in the eyes of your teenage daughter as she scans your dress and gives you the unspoken "what are you wearing?" look. Not everyone has children so they have to pick up clues elsewhere. Any man over the age of 40 who has more than one pair of trainers really should have a word with himself.

Ask yourself, what would Sinatra do? He had two modes of dress. One was immaculately suited and booted. The other was immaculately suited and booted but with tie slightly loosened. This was no accident. What this look said is "I may be slightly relaxed at this moment but don't let this deceive you because my natural state is alert and ready for battle". The look adopted by Davie and Brittin yesterday didn't say anything quite as powerful as that.