At 11.30am precisely, a car pulled up outside 29 Gowan Avenue, Fulham, and a woman clutching a bouquet of red roses jumped out. Exactly a year after the television presenter Jill Dando was murdered on her doorstep, the woman laid the flowers down by the front gate, propped up against a bunch from another anonymous wellwisher.
With a catch in her voice she admitted that the presenter, who died from a single shot to the head at around 11.30am on 26 April 1999, had been a "good friend" before driving off down the deserted road.
On the first anniversary of Ms Dando's death, police returned to Gowan Avenue once again. Standing at intervals along the west London street, they stopped passers-by as they hurried under the driving rain, asking them if they regularly walked along this road.
Did they have any information, however trivial, that might provide a clue as to who killed the Crimewatch UK presenter? These are questions that many of them have no doubt been asked several times before and, if there is no breakthrough, may well be asked again.
"Exactly one year on, this is our first chance to see things as they were a year ago and talk to people who might have been here on the day in question," said one officer who has been working on the investigation since the start.
"We are talking to everyone who walks or cycles past, plus some drivers, and asking them if they can remember anything that might be useful.
"The killer may well have been in the area for a few days previously to find out exactly where Jill lived and people may have noticed something odd. Very often they don't come forward because they think that they don't have anything very important to say but it all helps us to build up a picture of what happened and why."
By the afternoon, 31 new witnesses had been uncovered and some three or four had given "relevant information".
Outwardly, all the police involved in the hunt for the murderer say they are confident that the killer will be found.
Privately, after a year of what has now become Scotland Yard's biggest murder investigation, some officers fear the case may never be solved.
They have interviewed 1,800 people, including all 486 listed in Ms Dando's Filofax. More than 4,000 people have been interviewed as witnesses or suspects and detectives have taken around 1,700 statements. Scotland Yard confirmed that at least 140 people with an "unhealthy" interest in the presenter have been identified, although most have been eliminated from the inquiry.
The investigation has cost £1.9m so far and people are still coming forward with snippets of information that need to be checked out, however trivial.
On Tuesday, a woman told police that she saw the man suspected of the murder loitering near Ms Dando's home an hour before she was killed. She saw a man in a dark suit carrying a mobile phone but only told police the day before the first anniversary of the presenter's death and then only when she was stopped in Gowan Avenue as part of the anniversary operation.
Recently officers tracked down two people, including a meter reader described by one witness and a man collecting his daughter from school, who had been in Gowan Avenue on that fateful morning.
Detective Chief Inspector Hamish Campbell, who is leading the inquiry, said yesterday that he was concerned and disappointed that people were still reluctant to contact police with what he described as "important information".
He said that another witness had given details which he wished he had had a year earlier and added that he firmly believed it would be a member of the public who would provide the vital clue.
In the bars and restaurants of Fulham, conversation still centres on the unsolved murder and everyone has their own theories.
These feature anything from Serbian hitmen taking revenge for the Nato bombing of a television station in Belgrade, a gangster angry at Ms Dando's work on Crimewatch, and the most recent - and currently the favourite - an obsessive stalker. Terry Benjamin, whose window installation shop looks straight down Gowan Avenue, said everyone talked constantly about the case. He said: "When you go out it's all anyone is talking about, even a year later. In all the local bars and restaurants you can hear people talking about it and coming up with their own theories.
"We do sit here and look at the people going past to see if anyone resembles the suspect. I think there is always a chance the police will catch him but then again he may have just left the country."
Det Ch Insp Campbell said it had also been considered that the murderer might be dead. He said: "Suicide was a line of inquiry we took right at the beginning and we did check suicide cases and inquests. But it is still possible."
Despite the lack of a really positive breakthrough, there is no question that any of the 45 detectives currently working on the case will be moved to other inquiries. Asked if he thought they would be making similar appeals for more witnesses this time next year, Det Ch Insp Campbell could only say: "I hope not."