Overview: How do you define an introduction?

When an argument about the commission from a sale is over the sum of £350,000, you know this is a dispute in a different league to your average suburban-semi transaction.

When an argument about the commission from a sale is over the sum of £350,000, you know this is a dispute in a different league to your average suburban-semi transaction.

Still, the essence of the row between Lakshmi Mittal, the billionaire steel magnate, and Adina Kohn, a property consultant, is the same as any involving a disputed commission. Ms Kohn reckons she is owed this figure after Mittal this year bought a £70 million Kensington house that she claims she introduced him to seven years ago.

The argument appears to hang on the small print of an agreement with no expiry date. In any agreement with an estate agent, vendors are advised to be quite certain of its terms and duration since commission is a regular cause of disagreement, but in the case of that between a client and a buying agent the time scale is likely to run for far longer. What exactly constitutes an introduction and how much more should you expect for your money?

Rupert Bradstock of Property Vision, an agency that searches, negotiates and advises, says that a typical question from a new client is, "What happens if we find a house first?"

"I tell them we would look at the circumstances," he says, then goes on to explain that by taking on a limited number of buyers and making sure they are not chasing the same kind of property, there is less chance of missing something.

Even so, house-hunting for the perfect property takes time - and if you are paying someone to do the foot-slogging, you can afford to be choosy. A contract with Property Vision is for a year and within that time a house can easily turn up by other means. The firm have recently negotiated a sale between two relatives; sometimes they will get the nod from clients that a particularly tasty property is about to become a casualty of divorce and could the agency check it out?

Bradstock says they regard themselves as trusted advisers rather than just buying agents, but whoever a would-be purchaser employs, they should look at the letter of the contract and not simply rely on a verbal agreement. "We would not be claiming commission after seven years," he adds.

But what if a situation involved a vendor and the period were seven months, well beyond the agreement with the selling agent? A reader who recently found herself with no shortage of buyers for her family home in London could find nothing to buy. After months of searching she took it off the market for almost eight months.

"Right at the beginning some friends said they wanted to buy," she says. "We referred them to the agent, even though they had not heard about it through him. They kept in touch with us and when we finally found somewhere we asked if they were still interested at an increased price. We went ahead with the sale and did all the negotiations ourselves. We did inform the original agents, if somewhat reluctantly given their non-existent role."

Although the vendors felt not to have done so would have been indefensible, they did draw the line at paying a multiple agency fee. "We said we would only pay the sole agency fee of 2.5 per cent."

Discussion of all the details from the beginning tends to prevent problems from arising, and agents who are familiar with cases of relatives popping up as private buyers have learnt to ask at the outset whether anyone at all is in the frame. Peter Young of John D Wood recalls one client using the usual trick of suddenly taking the house off the market. "I only found out years later, when the purchaser asked me to sell the same house and produced the details I had originally sent out."

Generally, estate agents accept that there are some they will lose; they can't keep checking on everyone who has ended an agreement to see whether they have sold to a buyer introduced a year ago by them. Then again, £70 million houses take rather longer to fade from memory.