Complex sentence: The company now known as the Whitechapel Bell Foundry dates back to at least 1570 but a continuous line of master founders in Whitechapel or nearby Aldgate exists since 1420.
Split into simpler sentences: The company now known as the Whitechapel Bell Foundry dates back to at least 1570. However, a continuous line of master founders in Whitechapel or nearby Aldgate has existed since 1420.