I agree with the modern historian approach (seems the most intuitive when possible) although exploring history from a postmodern perspective can be quite odd.

I remember in the book different photos showcasing the British coastline.

The author suggested that there is no way of knowing the exact size of the coastline because answers can be given in different measuring metrics. So, measuring it in kilometres gives no authority to suppose that kilometres is the absolute metric over metres (for example). Since there are so many possibilities and even different maps with different measurements of the coastline, the exact answer cannot be known. Yet, for this fact, the postmodernist would suggest that the British coastline does not exist, which is a radical claim to make. I am not sure if all postmodernists would agree to what I said, but this point in the book struck me as an interesting one for sure.