EXHIBIT 99.1 [THE DIALOG CORPORATION LETTERHEAD] News Announcement For Immediate release THE DIALOG CORPORATION APPOINTS ALLEN THOMAS, DEPUTY CHAIRMAN LONDON, England and CARY, NC--Dec. 21, 1998-- The Dialog Corporation plc (NASDAQ:DIALY), a leading information technology company, today announced that Allen Thomas, a non executive director, has been appointed Deputy Chairman of the Company's board of directors, effective immediately. Mr. Thomas is Chairman of Ockham Holdings plc and a Director of Penna Holdings plc. From 1972 through 1992 he was a partner in Paul, Weiss, Rifkind, Wharton & Garrison, a leading New York law firm, where he was the founding managing partner of the Hong Kong office and acted as General Counsel to the Municipal Assistance Corporation in the refinancing of New York City. The Dialog Corporation (http://www.dialog.com) is a leading provider of online information created by the merger of M.A.I.D plc and Knight-Ridder Information Inc. The Dialog Corporation brands include the DIALOG, DataStar and Profound range of products and services. These brands provide comprehensive, authoritative sources of information to professionals worldwide. The Dialog Corporation has world headquarters in London and US headquarters in Cary, NC. Its American Depositary Shares (ADS) are traded on NASDAQ under the symbol "DIALY" with four Ordinary Shares comprising one ADS; its Ordinary Shares trade on the London Stock Exchange under the symbol "DLG." CONTACT: The Dialog Corporation plc Sara Parker, Corporate Communications sara_parker@dialog.com 011-44-171-930-6900 Jaffoni & Collins Incorporated David C. Collins/Robert L. Rinderman U.S. investor relations dialy@jcir.com 212/835-8500 Courtney Darby/Jed Hamilton U.S. media contacts courtney@middleberg.com Middleberg + Associates 212/888-6610 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. Date: December 23, 1998 THE DIALOG CORPORATION PLC By: /s/ David G. Mattey -------------------------------- David G. Mattey Finance Director