There are a great many of us with endowment-linked mortgages.

I'm sure we're all concerned about the speculation of under-performing investments which might not pay off our mortgages.

Quotations nowadays have lower assumed growth rates by order of the regulator, currently between four and eight per cent.

On the face of it, growth rates could appear to be under-performing because the majority of endowment holders had the old assumed growth rates, which were between five and ten per cent.

Also, before the 1990s, endowment providers used a generic assumption for illustration purposes to show the insurance company's charges, called the Lautro-Life Assurance Unit Trust Regulatory Organisation's charges.

But this was used irrespective of the insurance company's own actual level of charges levied within the endowment contract.

In hindsight, this caused a lot of confusion with the true meaning of a quotation!

This was highlighted by an Argus Business reader who was so concerned about his endowment he asked me to investigate.

In 1990, this reader and his wife went along to the Nationwide Building Society to arrange their mortgage and was duly sold a Guardian Royal Exchange With Profits Endowment.

This showed the mortgage of £61,000 would be repaid after 25 years as long as the investment within the endowment averaged a growth of 7.7 per cent.

This advice, on the face of it, would appear to have been fair.

After all, 7.7 per cent is within the current regulator's level.

However, in 1996, this couple received a revised illustration stating the rules that govern how insurance companies calculate maturity values had changed from using "standard" to "actual" expenses used in the illustration.

The investment within the endowment would now have to grow at 9.4 per cent on average over the remaining term to meet the £61,000 mortgage liability in 2015!

This is a much better than expected outcome and quite surprising considering all the adverse speculation about endowment-linked mortgages.

In a statement, Guardian say: "During the past couple of years, the value of our With Profits Policies have increased by more than the required growth in 1996."

They go on to say the growth required for the policy to meet its target is less than six per cent and, in fact, at six per cent the assumed illustrated value will now be £62,400.

This just goes to show that not all endowments sold in the late Eighties or early Nineties were too bad.

Wilbury Financial Management is a member of IFA Network Ltd, which is regulated by the Personal Investment Authority.