The point is - "reports, not all facts" - that not everything we read in the media is true. Nothing in the media suggests she is "a cheap tart". If it did, I could understand what led to you forming such a derogatory opinion, of a lady with whom you are not acquainted. Unless you can provide proof, that Ms Mone is what you opined, you are maligning her character, and libel is punishable in a court of law.
Particularly as the definition of "tart" understood by most people is that shown in most dictionaries, i.e. 'a prostitute or promiscuous woman'. Good luck, Craftalot, with defending the use of that word to describe her in a public forum.