1902 Low and High Tide Pennies
Part way through the production of 1902 pennies, the reverse design was modified slightly. Until then, the same reverse design used at the end of the reign of Queen Victoria (Freeman reverse B) had been used. The new design was functionally identical but among other small changes, the sea line to the right of Britannia had shifted slightly. On the old design (Freeman reverse A) the sea meets Britannia's robes below the fold under the crossing point of the legs - the so-called low tide reverse. On the new design (Freeman reverse B) the sea meets Britannia's robes slightly above the fold under the crossing point of the legs - the so-called high tide reverse.
The mintages of the two separate designs are unknown but from 1969 to 1972, V.R. Court did a survey of post-Victorian British bronze penny varieties (p14, Court, Major Varieties of U.K. Pennies 1902-1967 in Coin Monthly, August 1972). In his survey of 3,893 1902-dated pennies he found 175 low tide pennies and 3,718 high tide pennies (p15, Court, Major Varieties of U.K. Pennies 1902-1967 in Coin Monthly, August 1972). By his survey it can be concluded that around 4.5% of 1902-dated pennies are low tide pennies: while they are scarce they are not rare.
The reason for the change is unknown but the reign of Edward VII saw five minor variations on the same penny reverse: no doubt the Royal Mint was trying to subtly improve the dies.