This clock represents the pinnacle of achievement in horology for the late 17C. How Thomas Tompion who made it acquired his outstanding scientific and technical skills is not known. The 'face' has a twenty four hour dial, three hands telling the hour, minute and lunar time. One is also able to see the age and phase of the moon, the time of high tide at London Bridge and the day of the month, as well as the sun's apparent position. The maker was so highly regarded that he was buried in Westminster Abbey, an extraordinary honour for a craftsman.