I see a few detractors, but for me, The Ipcress File mini-series remake was a great period spy drama.
This kind of show is a sum of its parts proposition. As a spy drama the story can't be too straight forward, it must deliver intrigue, conceal its feints, and deliver twists and turns.
I liked the original movie, but this mini-series earned its way too, and delivered. The period elements were also extremely well observed, from the ambience of early 60s cities and sets, through to the quality of lighting and filming that evoked a 60s spy romp and a little of the classic uncompromising and unsentimental quality of spy action and intrigue.
Each of the leads had moments to take centre stage and for the story to revolve around their role, something that for the most part worked well, with perhaps just a couple of lapses of awareness as to the possibilities of interpretation of what had transpired or was transpiring - but that is a criticism of script and not acting.
If you like a classic spy yarn, The Ipcress File shouldn't disappoint.