Scheduled Thomsonfly flights don't appear in OAG flight guides. When I asked OAG why, they said it was because TOM used a three-letter designator, which OAG's systems could not yet handle. Other airlines that only use a three-letter one and not a two-letter one - such as Air Southwest, WOW; and Manx2, BPS - also don't appear. (Although easyJet uses EZY, it also has U2, so is included.)
Both WOW and BPS have a very aware local business base and a more focused business product, which perhaps TOM doesn't at its more numerous bases.