Carl M. Olson established his studio in Rangströmsliden in 1882, so the photograph is taken after that.
There are four collections with a total of over 300 of his portraits here: http://www.genealogi.se/portratt/files/7.html
You can deduce some things from the text on the backside, and that is that by 1891 the text generally included the telephone number, and after 1894 it generally mentioned the prizes he won. So the photograph is likely done between 1882 and 1890.
Carl M. Olson died in 1900, but his widow ran the studio in his name until the 1930's. His collection of negatives was given to the City of Gothenburg in 1940, and here comes an intriguing part:
"Plåten Förvaras För Efterbeställning" means "Plate is stored for further orders", which means that the original negative plate of your photograph may be in the collection of the museum. It is surely worth calling them and asking them about it. Perhaps that collection includes extra information, like which year it was taken.
I can't find anything about Carl M Olson going to England. The book "Göteborgs Fotografer" by LarsOlof Lööf may have more information about Carl M Olson. It seems to be out of print, although you probably can find second hand copies, but of course it is in Swedish.
It does seem more likely that your ancestor visited Gothenburg some time between 1882 and 1890.