Lennon wrote the song taking inspiration from a nineteenth century circus poster for Pablo Fanque 's circus which he purchased in an antique shop on 31 January 1967 while filming the promotional video for the song `` Strawberry Fields Forever '' in Kent . Lennon was inspired to write the song by a 19th century circus poster for Pablo Fanque 's circus he purchased in an antique shop on 31 January 1967 , while filming the promotional video for `` Strawberry Fields Forever '' in Kent .