Hello Liz,
I think Lady Chater maybe simplified things a little.
Sala and Heby are two small towns some 100 kms (abt 60 miles) northeast of Stockholm (the capital of Sweden). They lie less than 15 kms (10 miles) apart; in fact the municipalities today share a border, although Sala is in the province of Västmanland and Heby is in the province of Uppland.
Granberga is/was a tiny village (by village I mean a couple of farms together) in the parish of Huddunge which today lies within the municipality of Heby. Huddunge by (by = village) is a proper little village with a church.
If Lady Chater was born at Granberga, she was born in the parish of Huddunge in the county of Västmanland (this is most important, everything is done by parish here).
I suspect Lady Chater felt that she had to say Heby or Sala because these places (especially Sala) can be found on a map - you have to have a very good map indeed to find the small village of Huddunge. Sala was once quite an important place since one of the most important mines in Sweden was located here, a silver mine. So chances were that some of her husband's business associates had at least a vague idea about Sala.
Today Sala has less than 14,000 inhabitants, Heby has abt 2,700 inhabitants. Huddunge parish has abt 500 inhabitants, which means that the village proper has even fewer people living there.
Here is a link to some pictures of preserved typical houses of this area:
http://www.sala.se/moklinta/gammelgarden.htm Unfortunately, the records for the county of Västmanland are not completely online yet. Since this is the case and since I live in the wrong part of the country I cannot search the records for you.
Maybe someone else here lives in Uppsala where the physical records for Huddunge are kept?
If you don't get an answer here within a few days, you can email the regional Archive in Uppsala (in English of course) and ask them to look for the birth record:
landsarkivet@landsarkivet-uppsala.ra.se
Ingela