I am not sure you can draw that conclusion.
If we had 1 infectious person and as a result of them going to Cheltenham they infected 10, whereas had they stayed at home they would not, then you have 10x the number of "seeds" out there. It depends where those seeds went. Perhaps they all came from north Wales and buggered off back there? And their relatives then went back to Scotland? It's all too far removed to say that because there is no spike (yet) in Cheltenham, then it did not matter.
No-one is going to convince me otherwise that holding an event like Cheltenham whilst there was a pandemic sweeping the world and the country, was a fucking insane idea. There should be the mother of all inquests about some of the decisions made and who made them, when all this is over. Now is not the time, but there are people with blood on their hands IMO.