The whole article and claims by Billy are littered with inaccuracies and simply smack of some nobody trying to get some money and kudos in the aftermath of the 2012 Olympics by making accusations linked to Seb Coe.
I have read a lot about Norman and he is almost universally disliked and seen as corrupt. If a British athlete got on the wrong side of him he could make it very difficult for them to compete on the European circuit. He was involved closely with Ovett in his (Ovett's) peak years and could use his influence to determine who was in the race and which races were run. Norman was responsible for setting up a Mile race at the 11th hour in Koblenz 81, as Coe had just broken Ovett's Mile WR a few days earlier. Ovett was down to run a 1500 there against Scott, but at the last minute they added a Mile to the programme also. Scott was apparently quite peeved, but went on to run and win the 1500 in 3:31.96, a US record at the time.
Even Coe was not exempt from Norman's influence, especially in the early part of his career. Coe ran and broke his first 1st WR in Oslo 79, despite not having permission to run there at the time. In 81, Coe could only get permission to run in a certain number of European circuit races, by agreeing to run a set number of races in the UK organised by Norman. He ran in 6 international matches in the UK that year as well as twice for Britain in the European Cup. Ovett had far more of a free rein to run where and when he pleased without any fear of repercussion.
Also in 81, Coe, who was originally down to run an 800, tried to get into the field for the Dream Mile in Oslo, in which Ovett was running. He was told he could not by Andy Norman, who promised they would meet later that season in the Brussels Golden Mile instead. Coe subsequently ran a 1000m there and broke the WR. Years later Norman claimed (and was quoted) that Ovett had not wanted to race Coe in Oslo, although Ovett said it was all down to Norman. A few days before the Brussels Mile, with everyone expecting a Coe/Ovett clash, Ovett pulled out of the meet and ran a 1:47 800 in Norway the day after instead. This was either in "The Perfect Distance" or Coe's biography from 1992.
I have also heard claims that Norman even had influence over the rabbits chosen for Coe's races and that in some cases told them to hinder rather than help in his world record attempts. This particularly applies to James Robinson, who gave Coe a 51.5 and 1:47.4 in July 81 for his 1500m WR attempt, but the next month was able to give Ovett a 56 and 1:53 in his Mile WR!
Getting back to Billy's claims. For a start his fastest 800 that year was only 1:45.27 when coming 5th at Crystal Palace in July. His career pb of 1:44.65 went back to 84.
In the 3 weeks prior to his race with Coe at the Palace, Coe had run the 2nd fastest 800 of the year, 1:43.38 and had almost won the World Cup 1500 title, narrowly beaten by the then World Champion, Abdi Bile, after a push on the last bend. So while not at his vintage best, he was still one of the very best in the world and almost 2 secs faster than Billy.
Moreover, the comment that Ikem Billy had been unbeaten by a Brit all season is also untrue. He had already been beaten by Coe himself in Rovereto in July that year. In fact Billy only beat Coe once in his career and that was in the final of the 1990 Commonwealth Games where he finished 5th, one place above Coe who was suffering from a chest infection and told not to run.