Occasionally, putative entrepreneurs ask me whether they should quit their job to start a business or do it part-time while keeping their current job. I usually suggest the latter strategy, because it worked for me. For six years after university, I was employed by other people – all the while moonlighting on my own projects, such as pubs and software companies, in the evenings, during weekends and holidays. I didn't take many vacations in my 20s, as I was too busy managing various ventures on the side.

The turning point came when a memo was circulated at Kleinwort Benson where I worked, stating that staff were not permitted to hold directorships or shareholdings in external companies. I knew then the time had come to take the plunge and embrace full-blown self-employment, so I jumped ship the following month and became independent. My sense of freedom was palpable, but I didn't regret the years juggling employment and entrepreneurship. It was part of my apprenticeship.

The advantages of holding down a job while plotting to become an entrepreneur are plain. You learn at someone else's expense; you receive an income to pay the overheads while your business develops; and you hedge your bets in case your freelance activities fizzle out. The disadvantages are also clear: if you get caught by your boss misusing resources or getting distracted from the day job, there will be trouble; and a business run in your spare time will never receive the focus and devotion it needs to be truly successful. If you are ambitious, the part-time option should only ever be temporary. You should have a “boat-burning” target: the point at which you chuck the job and dive in.