I heard a moan about The Apprentice this week. Not the usual one about it being ‘unrealistic’ and ‘more about entertainment than business’. As I’ve said here before, I tend to agree. No, this time, Sir Alan’s primetime smash was being knocked because ‘all the challenges this series are about selling, not all the other skills you need’.

I’m going to break the habit of a lifetime and defend The Apprentice. Now selling might not be the only important skill an entrepreneur needs, but it sure is the one you can’t do without.

If you can’t convince someone your product, service or time isn’t worth paying for then frankly you’re simply not cut out to be running your own business. When you take away everything else, selling is at the core of every business – and social enterprises, even charities, are included in that.

A good idea, or even a good idea people want, isn’t even a viable, let alone, good business, until you can convince those people to pay for it – or at least someone else to pay for them to use it in the form of advertising.

Not every entrepreneur is the hardnosed salesperson, of course. Nor do you need to be. But you need to be able to sell your business – it must have a sales story you believe. If you can’t sell it to yourself, then even the most silver-tongued highflier won’t be able to sell it to anyone else.

Selling isn’t just about grabbing the cash (well it is, but let’s digress), it’s about establishing a proposition that appeals to a clearly defined customer, almost certainly a bank manager and later investors, and, increasingly, a workforce.

You’re always selling as a business owner. The time you’re no longer looking to reinforce your company’s proposition to one of those crucial stakeholders and new markets is the time you’ve lost motivation and need to move on.

That’s why The Apprentice is right to focus on sales. Over the past few weeks the teams have competed on selling fish direct to shoppers at a market getting, to grips (or not) with pricing and face-to-face negotiation; taken over running a pub menu for a day, creating a theme (or mini brand) and marketing it; run an industrial laundry service securing b-2-b business on a trade scale; and just last week creating an ice cream product from scratch and securing orders in advance.

The theatrics and bitching that proceed might take The Apprentice more into Big Brother territory than any kind of business lesson, but we know that. That’s why it’s a primetime winner.

There’s nothing wrong with the challenges, though, especially as sales is at the root of them all. Teamwork, leadership, decision-making, analytics – they all come out in the wash. Ask any entrepreneur and, as Sir Alan will verify, they’ll tell you it’s sales that count.