John Krasinski thinks his father-in-law is the ''greatest human ever''.

The 40-year-old actor - who is married to fellow Hollywood star Emily Blunt - recently shot the second season of 'Tom Clancy's Jack Ryan' in London, and John loved being able to spend quality time with Emily's beloved father, who lives in the city.

Asked about the experience of shooting the series in London, John explained on 'Late Night with Seth Meyers': ''My favourite part of the day was going back to my father-in-law. By the way, my father-in-law is the greatest human ever.

''He's got the greatest accent and he's so impassioned about everything.

''So, he was like, 'What did you get up to today, Johnny?' and I was like, 'Oh you know, I was running on some rooftops and then a guy jumps into the Thames.'''

Then, John - whose wife was born in London - did an impression of his father-in-law, delivering his best British accent in the process.

The Hollywood star recalled: ''He was like 'Really?! That's absolutely wonderful! Good for you. That's fantastic! Fantastic.'''

Meanwhile, John recently confessed that a healthy work-life balance is the key to his happy marriage.

The actor - who married Emily in 2010 and has kids Hazel, five, and Violet, three, with the actress - said: ''I gotta say it just sort of happens organically.

''It's one of those things where I was a huge fan of hers before I even met her, so I continue to be a huge fan of hers in everything she does.

''So we're just extremely supportive, we get what the job is and that you gotta travel and do some stuff, but it's always about coming back home and being together - it's the most important thing.''