recording of Carnival of Monsters (1973), requiring a new prop to be built for the rest of the season; The Three Doctors was recorded after Carnival, but set before it, so the screwdriver could be seen to revert to its previous appearance for one story after The Three Doctors before receiving a more permanent redesign thereafter. During the first three years of the Fourth Doctor's tenure, producer Philip Hinchcliffe further reduced the use of the sonic screwdriver. Exceptions include Robot (which was the last story to be produced by Barry Letts), where it was again used to detonate mines, and as a "miniature sonic lance" to cut out a lock. Aside from unlocking doors, the device was greatly downplayed during the Fourth Doctor's second and third seasons. It saw a resurgence once Graham Williams took over as producer in 1977. In the final story of season 15, The Invasion of Time, the Fourth Doctor conceded, "Not even the sonic screwdriver can get me out of this one." It featured regularly in season 16 during the Key to Time saga. The Doctor's Time Lady companion Romana constructed a sonic screwdriver of her own similar to the Doctor's. It is depicted as being smaller and sleeker than the Doctor's, and he was sufficiently impressed with her design that he attempted to swap screwdrivers with her in The Horns of Nimon (1979–80). By season 18, both script editor Christopher H Bidmead and producer John Nathan-Turner were eager to downplay the device as much as possible. The sonic screwdriver was written out of the series late in season 19, in the Fifth Doctor serial The Visitation (1982). It is destroyed by a Terileptil to prevent the Doctor from escaping a holding cell; in response, the Doctor sorrowfully remarked, "I feel as if you've just killed an old friend." Eric Saward later explained in a 2005 DVD interview that this was done on the instructions of producer John Nathan-Turner. Saward had written out the sonic screwdriver, believing that the Doctor had "a cupboard full of them" in the TARDIS. On the basis that a device that could help in any situation was very limiting for the script, Nathan-Turner decided that it would not return. The Tenth Doctor joked about the Fifth Doctor's lack of sonic screwdriver in the mini-episode "Time Crash" (2007), commenting that he "went hands-free" and could "save the universe using a kettle