Complex sentence: Dollond & Aitchison are the longest established opticians in the United Kingdom, having been established in 1750 by Peter Dollond in Vine Street, London, and been joined by his father John Dollond in 1752.
Split into simpler sentences: Dollond & Aitchison are one of the oldest opticians in the United Kingdom, having been established in 1750. He was joined by his father John Dollond in 1752.