Terrance Dicks (in-universe)

After a Doctor Who fan managed to contact 1970s UNIT and discussed 2020 with the Third Doctor, Jo Grant and the Brigadier, a fourth caller still on the UNIT line complimented the Doctor, Jo and the Brigadier's wise words and then called for a round of tea. (WC: U.N.I.T. On Call)

Behind the scenes

 * This caller was voiced by Jon Culshaw in his regular voice. Although the dialogue is ambiguous, one possible interpretation of the webcast is that the fan had in fact merely reached Culshaw and that he had been impersonating the Doctor and Lethbridge-Stewart (and possibly Manning).