They have been tardy in acknowledging the importance of Allen's work.
Advanced English Dictionary
+adjective ~ (in doing sth) (formal) slow to act, move or happen; late in happening or arriving: The law is often tardy in reacting to changing attitudes. + people who are tardy in paying their bills + (AmE) to be tardy for school tardily adverb tardiness noun [U]: the tardiness of the company's response
Random quote: Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more.: Nikola Tesla