The mug is titled:

AN EAST VIEW OF
Liverpool Light House & Signals on Bidston Hill

Below this inscription are depicted the lighthouse and a row of flags each numbered 1-58 and then below that is the list of owners of each flag thus:
1. Mr. Clark's
2 Mr. Leyland's, etc.

Reference: In 1763 a signal house on Bidston Hill was first mentioned - although Bidston had probably been used as a lookout from pre-Roman days. A telegraph service was set up to give early notice of the arrival of ships in the Port of Liverpool. Over one hundred signaling poles were erected, extending from north of the lighthouse to beyond the windmill, belonging mainly to the merchants in Liverpool. As the ships carrying their cargoes were spotted out at sea, the relevant flags were raised and could be seen from Liverpool. The advance knowledge of their ships' arrivals enabled the owners to hasten the unloading of their cargoes. In 1771 the first Bidston lighthouse, an octagonal structure, was built. The Government established a chain of stations fitted with semaphore signals, between Bidston and Holyhead, in order to 'give alarm upon any intelligence of an enemy'. It took only eight minutes to transmit messages from Holyhead to Liverpool. In 1791 the wooden windmill was destroyed in a gale and was replaced by the present one.

Circa 1785-1800.