While waiting in London for some situation presenting itself, Mr Perry amused himself by writing fugitive verses and short essays for a journal, called the "General Advertiser." These he dropped into the letter-box of that paper, as the casual contributions of an anonymous correspondent, and they were of such merit as to procure immediate insertion. It happened that one of the parties to whom he had a letter of recommendation, namely, Messrs Richardson and Urquhart, were part proprietors of the Advertiser, and on these gentlemen Mr Perry was in the habit of calling daily, to inquire whether any situation had yet offered for him. On entering their shop one day to make the usual inquiry, Mr Perry found Mr Urquhart earnestly engaged in reading an article in the Advertiser, and evidently with great satisfaction. When he had finished, the former put the now almost hopeless question, Whether any situation had yet presented itself? and it was answered in the usual negative; "but," added Mr Urquhart, "if you could write such articles as this," pointing to that which he had just been reading, "you would find immediate employment." Mr Perry glanced at the article which had so strongly attracted the attention of his friend, and discovered that it was one of his own. He instantly communicated the information to Mr Urquhart; and at the same time pulled from his pocket another article in manuscript, which he had intended to put into the box, as usual, before returning home. Pleased with the discovery, Mr Urquhart immediately said that he would propose him as a stipendiary writer for the paper, at a meeting of the proprietors, which was to take place that very evening. The result was, that on the next day he was employed at the rate of a guinea a-week, with an additional half guinea for assistance to the "London Evening Post," printed by the same person.

On receiving these appointments, Mr Perry devoted himself with great assiduity to the discharge of their duties, and made efforts before unknown in the newspaper establishments of London. On the memorable trials of admirals Keppel and Palliser, he, by his own individual exertions, transmitted daily from Portsmouth eight columns of a report of proceedings taken in court, an achievement which had the effect of adding several thousands to the daily impression of the paper. Even while thus laboriously engaged, Mr Perry wrote and published several political pamphlets and poems on the leading topics of the day, all possessed of much merit, though of only transient interest.

In 1782, Mr Perry commenced a periodical publication, entitled "The European Magazine." This work, which was on a plan then new, comprising a miscellany on popular subjects and reviews of new books, appeared monthly, and from the ability with which it was conducted, added greatly to the reputation and popularity of its editor. Having conducted this journal for twelve months, Mr Perry was, at the end of that period, chosen by the proprietors of the Gazetteer to be editor of that paper, in which shares were held by some of the principal booksellers in London, at a salary of four guineas per week; but under an express condition, made by himself, that he should be in no way constrained in his political opinions and sentiments, which were those of Mr Fox, of whom he was a devoted admirer. While acting as editor of the Gazetteer, Mr Perry effected a great improvement in the reporting department, by employing a series of reporters who should relieve each other by turns, and thus supply a constant and uninterrupted succession of matter. By this means he was enabled to give in the morning all the debates which had taken place on the preceding night, a point on which his predecessor in the editorship of the Gazetteer had frequently been in arrears for months, and in every case for several weeks.

One of Mr Perry’s favourite recreations was that of attending and taking part in the discussions of debating societies. In these humble, but not inefficient schools of oratory, he always took a warm and active interest, and himself acquired a habit of speaking with singular fluency and force; a talent which procured him the notice of Pitt, who, then a very young man, was in the practice of frequenting a society in which Mr Perry was a very frequent speaker, and who is said to have been so impressed with his abilities as an orator, as to have had an offer of a seat in parliament conveyed to him, after he had himself attained the dignity of chancellor of the exchequer. A similar offer was afterwards made to Mr Perry by lord Shelburne; but his political principles, from which no temptation could divert him, prevented his accepting either of these flattering propositions.