I often heard that Norway was something akin to Saudi Arabia or the OAE in terms of wealth before it discovered oil. I thought so too. The data shows that it was not the case. Of course, Paul Bairoch was not the only economic historian, as, in contrary, the Maddison project's data claims that Norway while being prosperous, by no mean could be called ultrarich in the first half of the 20 century.
It's just checked to see what number I could find. Here is a calculation of historic Norwegian GDP in local currency inflation adjusted to 2005 prices:
https://www.ssb.no/a/histstat/aarbok/ht-0901-bnp.html
The exchange rate for the same year is 6.45. So you'll see 1938 per capita GDP (no PPP adjustments) in 2005 numbers would be US$9,627.
That's a quite respectable GDP, and not the starvation prone image often depicted of Norway pre oil.
By 1938, the economy had transformed from an agricultural to a manufacturing one. In addition Norway had major mining industries, and came out if WWI with a huge merchant fleet.
The Social Democratic Party had their first government from 1928, and the work that led to the welfare state had begun.
But ultrarich? That's hardly a description of Norway at any point in time. (And GDP is anyway no good measure for rich. It doesn't measure assets.)