So far I've been achieving this in the file before uploading by using concatenate(a1," ",b1," ") etc. You could replace the space in the "" with a comma though, then pasting the result, as I've not yet found a way to do this in Workbooks.

Yes...

Here's some background information.  An example follows:

Separate Columns within a CSV import file can be concatenated into a single field in Workbooks.  E.g. first name and last name can be concatenated to populate the name field.  Separate address lines can also be concatenated, and you can choose the separator - a separator is the character that separates the values - it could be a comma, a space, new line / carriage return, or a custom character like a semicolon.

Example:

Start with a CSV file with well named column headers:

Click Start > Import > People > Select the CSV file > Click Next > Click Next again.

The Name fields have been automatically mapped.

You'll need to manually map the street address fields and specify the concatenation settings.

Scroll down on the right hand side > select Street Address > set the Mapping Type to 'Concatenate Fields from Source File'.

Select a suitable Concatenated Field Separator.

Add the address fields that are to be concatenated.

Also map address town to Person: Town or City > Click Next > Click Run.

Select the Imported Records tab and click Joe Bloggs' name to open his record.

The name and address fields have been nicely concatenated