Thanks for the information, both yourself and the other posters that took time to bring me up to speed. I think that the book that I bought was a translated copy of Mr Larssons work.
Declan
The US converted to metric wherever feasible in 1975. http://lamar.colostate.edu/~hillger/laws/metric-conv.html
Shhhh. Don’t tell anyone. The tea baggers will lose their fluid.
As I understand it, the way it happened was at around 5 or 6 AM on the date the switch was supposed to occur, everyone on the road stopped, carefully scooted across the road to the opposite lane, and continued driving.
No traffic was allowed on the night of the switch except buses, taxis, fire engines and such and five to five even those stopped, waited for five minutes and then continued on the other side. IIRC this traffic ban continued the whole next day. The reason for this was that an army of workmen uncovered new signs and removed old ones.
Here’s a photo from central Stockholm taken at the switch-over.
As for road markings the old ones were yellow and the new white so they co-existed for a while until the old ones wore off.
ETA The ten kilometer mil is also used in Norway.
MODERATOR NOTE, not a warning
Second Stone. You’re in General Questions. Bringing in politics is out of place. Try not to do this.
samclem Moderator, GQ
No cite, but as I’ve understood it, the switch was made due to pressure from Volvo and SAAB, who were having a bother to produce different cars for the domestic and export markets.
Those damn reasonable Scandinavians! 
I doubt that. They already had to make LHD cars for export, and even after the switch there remained the major RHD markets of the UK and various other countries. They still make RHD versions of their cars, in big numbers.
Do you imply that they made RHD cars for domestic use? 
As zwede has already pointed out most vehicles, the exceptions were mainly buses and post office cars, were already LHD.
According to this page (in Swedish), supposedly a transcription from a 1967 publication, the main reason was increased cross border traffic with all right side drive neighbours in a right side drive Western Europe. It was first suggested by comity in 1927, then in 1934, 1939, 1941, 1943, 1945 and 1953.
And as the prevalence of that term is due to the old Norwegian and Swedish “mile” being around that length (11 295 meters and 10 688 meters respectively), even if we hadn’t been metric, they’d have to convert our miles when translating to English.
But of course, if one is being contrafactual one might as well suppose a standardisation on the Imperial measurements outside of the English speaking world, as assume everyone would just stick to every one of their totally incompatible units.
I have leafed through a 17th century (English?) encyclopedia that gave all distances in whatever mile was used in the country being described; French miles for France, German miles for Germany, Irish miles for Ireland, English miles for England etc. Sweden was IIRC 3 to 4 days’ horse riding broad.
Consider my ignorance fought =)