What significant role did Richard Neville play in English history?

Richard Neville played a pivotal role in English history as a key figure in the Wars of the Roses, a series of dynastic conflicts that took place during the 15th century between the houses of Lancaster and York. Often referred to as "the Kingmaker," Neville was instrumental in the rise and fall of several kings during this tumultuous period. His influence extended through strategic alliances, political maneuvering, and military engagement, as he shifted loyalties at various points between the rival factions.

Neville’s actions included aiding Edward IV of the House of York in his ascent to the throne and later playing a significant role in deposing him. This capacity to orchestrate important political changes earned him his notable title. Thus, his role during the Wars of the Roses significantly impacted the political landscape of England, making this the correct answer in understanding his historical importance.

The other choices do not accurately reflect his contributions or impact. While he did have a powerful influence in royal affairs, he did not self-proclaim himself as king nor was he a botanical scientist. His involvement with the Royal Society also does not apply, as its founding occurred much later in history.