Forbes (Forbes & Hanley, 1849) knew of T. testudinalis at many places in Scotland but not in England. He predicted the range expansion southwards which reached the Farne Islands by 1856, Roker by 1857 (Tate, 1863 in Foster-Smith, 2000); Hesleden by 1861 (Dove Marine Laboratory manuscript, 1862, in Foster-Smith, 2000); Hartlepool by 1863 (Hancock, 1863, in Foster-Smith, 2000); Sandsend by 1901 (Lebour, 1902); and Flamborough before 1910 (Hargreaves, 1910).
APPENDIX re range advance/retreat: flic.kr/p/2jW74ig