Complex sentence: Despite the vast area covered, Tamsen was ideally positioned, either personally or through agents, to obtain news of new stamps, including surcharges and provisional issues and to obtain them either mint or by having them posted to him on cover.
Split into simpler sentences: Despite the vast area covered, Tamsen was ideally positioned, either personally or through agents, to obtain news of new stamps. These included many surcharged and provisional issues and Tamsen obtained them either mint or by having them posted to him on cover.