From Chapter 4:
There is a curious entry in Thomas Burton's diary of the proceedings of Cromwell's Parliament, which suggests that there may then have been the luxury of a members' smoking-room. Burton was a member of the Parliaments of Oliver and Richard Cromwell from 1656 to 1659, and made a practice—for which historical students have been and are much his debtors—of taking notes of the debates as he sat in the House. Members sometimes objected to and protested against this note-taking, but Burton quietly went on using his pencil, and though his summaries of speeches are often difficult to follow, argument and sense suffering by compression, he has preserved much very valuable matter. Referring to a debate on January 7, 1656-57, on an attempt to go behind the previously passed Act of Oblivion, the diarist records that "Sir John Reynolds had numbered the House, and said at rising there were 220 at the least, besides tobacconists." This can only mean that there were at least 220 members actually present in the House when it rose, not counting the "tobacconists" or smokers, who were enjoying their pipes, not in the Chamber itself, but in some conveniently adjoining place, which may have been a room for the purpose, or may simply have been the lobby referred to above in the extract from "Mercurius Pragmaticus."

From Chapter 6:
But so early as 1655 there is a sign of change of custom—a change, that is, in the direction of restricting and limiting the hitherto unbounded freedom granted to the use of tobacco. The London Society of Apothecaries on August 15, 1655, held a meeting for the election of a Master and an Upper Warden; and from the minutes of this meeting we learn that by general consent it was forbidden henceforward to smoke in the Court Room while dining or sitting, under penalty of half a crown.