In his book, Roobarb: An Illuminated Biogwoofy, Calveley describes how the real dog would leap up into the fork of a tree and how the dog's antics became part of the cartoon's opening title.
ɪn hɪz bˈʊk, ɹˈuːbɑːɹb: ɐn ɪlˈuːmᵻnˌeɪɾᵻd bˌaɪoʊɡwˈuːfi, kˈælvɛli dᵻskɹˈaɪbz hˌaʊ ðə ɹˈiːəl dˈɑːɡ wʊd lˈiːp ˌʌp ˌɪntʊ ðə fˈɔːɹk əvə tɹˈiː ænd hˌaʊ ðə dˈɑːɡz ˈæntɪks bɪkˌeɪm pˈɑːɹt ʌvðə kɑːɹtˈuːnz ˈoʊpənɪŋ tˈaɪɾəl.