Confessions of an Estate Agent: 'I saw it right away: a grey streak on the marble floor'

"It was a truly fabulous property: Hanover Terrace, overlooking the ponds in Regent's Park – white stucco, three storeys, five fireplaces, six bedrooms. Worth a substantial, seven-figure sum. The owner had gone abroad for a couple of years and we were refurbishing the property for the director of a top international credit-card company. The carpets alone cost a small fortune.

Susan Gilbert, letting associate at Knight Frank's Hampstead office

"It was a truly fabulous property: Hanover Terrace, overlooking the ponds in Regent's Park – white stucco, three storeys, five fireplaces, six bedrooms. Worth a substantial, seven-figure sum. The owner had gone abroad for a couple of years and we were refurbishing the property for the director of a top international credit-card company. The carpets alone cost a small fortune.

"There are always hassles with such a big job and this was no exception. For weeks we had tradesmen coming and going – decorators, carpet fitters, curtain contractors, plumbers, electricians and chimney sweeps. The dining-room walls were a deep red and each time they were painted, the original colour would show through after a couple of days. It took four coats to stop the bleeding.

"The chimneys were the biggest headache. They'd never been stripped and were still lined with the original horsehair. We had them swept, but they were still coated with soot and every gust of wind would blow coal dust into the rooms, all over the new carpets. Still, three months and £50,000 later, the work was finished. The house was immaculate and the client was all set to move in the following week. So I went round with the curtain fitter, Nigel, to give the house the once-over. Nigel was there to fix the curtain pulls – the final touch.

"When I opened the front door and walked into the hall, I saw it immediately – a grey streak, right in the middle of the marble floor. Bird droppings. No doubt about it. At first, I couldn't imagine what had happened. But as we went from room to room, the truth dawned. I couldn't believe my eyes. Every room was worse than the last. It was all over the curtains, in the baths, on the blinds in the top bedrooms and, worst of all, on my beautiful cream carpets. There were bird droppings everywhere. While Nigel followed behind, moaning disconsolately, I ran from room to room shouting, 'No, no, NO!' I was mortified.

"As I reached the third-floor landing, I let out an almighty scream. I'd found the culprit – a huge mallard duck, now lying at the top of the stairs, his struggles at an end. Poor thing – he must have stopped for a rest on his way to the park and somehow fallen down one of the chimneys. But of all the chimney pots to sit on, why did he have to sit on mine?

"All's well that ends well – except for the duck, of course. We got the cleaners back in and within days the house was perfect again. Nobody ever knew the difference. But, personally, I won't forget that duck in a hurry."

Knight Frank 020-7431 8686