The newest season of Professor T is reported to start on Sunday, August 24, 2026 on PBS Masterpiece, according to a recent public post about the premiere.

What’s known

  • A public listing says season 4 returns on August 24, 2026.
  • Another listing from WPBS says the same season 4 premiered in the U.S. on August 24, 2025 , so there appears to be conflicting information across sources.
  • Because of that mismatch, the 2026 date looks like the latest reported start date , but it is not fully consistent with other recent coverage.

Practical read

If you mean the next U.S. broadcast run , the safest answer is: late August, with August 24 being the clearest date currently circulating.

If you want the UK ITV release , the available reporting is different and appears less settled.

Region| Reported start| Notes
---|---|---
U.S. / PBS Masterpiece| August 24, 2026 1| Latest public post says season premiere.
U.S. / WPBS| August 24, 2025 2| Earlier press release says season 4 premiere.
UK / ITV| Not firmly confirmed 89| Coverage suggests delay/uncertainty.

TL;DR: the latest reported start date is August 24, 2026 , but there’s conflicting reporting, so treat it as tentative until an official network announcement.