BA#BACustomerService~What is the 24 hour rule for British Airways?

The 24-hour rule for British Airways allows passengers {+𝟒𝟒 𝟖𝟎𝟖 𝟏𝟎𝟏 𝟏𝟓𝟓𝟒(𝑼𝑲)} who book directly with the Airways to cancel their flight within 24 hours{+𝟏(𝟖𝟕𝟕)𝟔𝟗𝟑-𝟒𝟗𝟕𝟕(𝑼𝑺𝑨)} (USA) of making the booking and receive a full refund without any penalties.