[Pedantry] JH Whitley declined the offer of a peerage in 1928 and his successor died in office (his wife was made a Vicountess instead); Harry Hylton-Foster also died in post and the peerage went to his wife.He'll be the first speaker never to be elevated to the Lords.
The only speaker who lived for a significant time after his retirement not to get a peerage (Sir John Cust would've been offered one, but died five days after stepping down) was Arthur Onslow, the longest-serving Speaker of the Commons (33 years). There are differing accounts as to how well-regarded he was; some say he was admired for his integrity, others that both sides of the Commons mistrusted him. The king gave him a pension which works out at about £645,000 per year in today's money, so the lack of a peerage probably didn't distress him that much, if it bothered him at all. [/Pedantry]