First, that it is a jolly good idea to hold some shares, rather than keeping all your savings in the building society. Records of past returns support this: over longer periods, returns from shares have beaten inflation far more successfully than has the savings account.
But then the investment company will go on to tell you that his service is better than another company's. It will parade before you its investment team's experience, expertise and excellence; and it will demand a professional's fee. This could be thought cheeky, because there is evidence to suggest that most fund managers do no better than a monkey with a pin. Hardly any succeed in matching even what seems like a moderate target, the average return off the stock market. In the UK this is measured by the FTSE-A All-Share index.
Looking at the most common type of investment fund for savers, the general UK unit trust, not one managed to beat the index in the year to March. That is out of a total of 134 funds. Over five years, only five out of 117 trusts in this category succeeded in beating the index.
The best returns tend to come from index-tracking funds, which aim to match the performance of the stock market rather than claim to be able to beat it. These charge the investor much less, in part because they are run by computers. While pounds 100 in the average general unit trust made you pounds 17 in the year to March, the Gartmore UK Index unit trust, an index tracking fund, made pounds 27, only pounds 2 less than the index.
The managers with the best records will retort that the really intelligent ones can beat the index. But few of them can show enough consistency for comfort. Investors Chronicle, the weekly stock market magazine, recently examined all the unit trusts in the growth-oriented UK category that beat the index in the last six months. To be kind to the fund managers, we ignored initial charges: 72 out of 151 funds beat the index, on figures from the performance measurers, Micropal. We then took the 42 that had a nine-year record, and found that only five had outperformed the index in more than half the six-month periods in that time.
Among the best five was Fidelity Special Situations, managed by Anthony Bolton. "I passionately believe in active fund management. If I didn't, I wouldn't be doing it," he says. Mr Bolton's fund beat the index in 13 out of the 18 six-month periods. However, even here, the laws of probability take some shine off this. Probability says that in a sample of 40 managers picking stocks at random, two should beat the index 13 times out of 18 anyway. Mr Bolton's fund is one, Pembroke Growth the other.
An academic theory called the "efficient market hypothesis" supports this view that fund managers who beat the average return do so by chance. It says that in developed stock markets, such as the UK's, there are so many professionals digesting information that it gets almost instantly into the share price. No fund manager can often be in the position of finding valuable information and acting before everyone else. The theory draws evidence from the performance of fund managers, and also from mathematical studies of price movements.
If the efficient market theory does hold true for the UK stock market, then PEP investors could well be best advised to opt for index-tracking funds. The one with the most accurate tracking record is Gartmore's. Legal & General runs the cheapest, with no initial charge and a 0.5 per cent annual fee. That compares with the active funds, which tend to charge 5 per cent initially and 1 to 1.5 per cent a year.
q Catherine Barron is personal finance correspondent at `Investors Chronicle'.