As a private consultant or tradesman, you may have been in business for many years without seeing the need for your own website. Indeed, you may feel that it would bring in enquiries for new work which you don't need, and wouldn't have the time to reply to. 

But...
...times change, and your customers getting are used to looking for information on the internet, even if it is something as simple as your phone number - and if they can't find you, they may well choose someone else instead. You've now lost that customer!

Also, if you don't have a web address on your letterhead or business card, and your competitors do, your customer may wonder if you are able to keep pace with current technology, and may start to ask other questions regarding your competence.

And finally, a web presence is a great way of getting new business!