Double Olympic gold medalist Kelly Holmes suspects she never ran in an Olympic or World Championships race which did not include a drugs cheat and feels she was robbed of further titles.
Holmes won 800 metres and 1500m gold at the Athens Olympics 12 years ago, as well as two Commonwealth titles in a successful career on the track.
The 46-year-old Brit also claimed an Olympic bronze in Sydney, along with two World Championship silvers and a bronze.
Holmes is in no doubt she was robbed of more gold medals by rivals who she believes were guilty of doping.
She said: "I know I have missed out. All those bronzes and silvers, I know the people above me have cheated.
"I could have won more gold medals, definitely. What makes me prouder is that I've beaten lots of people who have cheated. Look at my Olympic 1500 metres gold medal - who came second? Tatyana Tomashova [who was later banned for doping offences].
"Over my career there are people who have beaten me that have cheated or allegedly were cheating or have been done for doping since. [Only] the Commonwealth Games, I reckon, I was probably up against clean athletes."
Holmes gave the example of American 1500m athlete Regina Jacobs, banned in 2004 after testing positive for THG, as a rival who was not adhering to the rules.
She added: "If you've been in a sport for a long time and you get one person who used to come fifth or sixth all the time and suddenly they win everything it's a bit suspicious.
"Somebody who is almost 40 and never broke four minutes [for 1500m] in her life becomes world record holder indoors. Is that not suspicious?"
Holmes will run in the London Marathon for the first time on Sunday.
"I'm not racing anyone but myself and any big bird that runs past me!" she quipped.