The groat is a fourpence coin. Circulation issue groats (like this one) had the Britannia reverse; Maundy Groats did not.
The fourpence denomination was discontinued after 1858, with the single exception of 1888 when a small number were issued for use in British Guiana and the West Indies.
In 1840 the value of the British Guiana guilder was fixed at 1 shilling and 4 pence (16 pence) and as a result the 4 pence piece was equated to the important 1/4 guilder denomination, known in British Guiana as a 'bit'. The 4 pence or groat therefore became the principle coin circulating in the colony although 3 pence, 2 pence and 1 1/2 pence silver coins were also provided. Although the standard design of the Imperial groat, the 1888 coins were struck only for British Guiana and the West Indies. They featured the Jubilee head of the Queen, not used for circulation coinage on this denomination elsewhere.
The groat remained in circulation in British Guiana right up until that territory adopted the decimal system in 1955.