If Flying Scotsman had 20 more carriages than Norwich, and Norwich had 100 carriages, then Flying Scotsman had 100 + 20 = <<20+100=120>>120 carriages.
Together, Flying Scotsman and Norwich had 120 +100 = <<120+100=220>>220 carriages.
If Euston had 130 carriages, 20 more carriages than Norfolk, Norfolk had 130 - 20 = <<130-20=110>>110 carriages.
Together, Euston and Norfolk had 110 + 130 = <<110+130=240>>240 carriages.
Altogether, Euston, Norfolk, Norwich, and Flying Scotsman had 240 + 220 = <<240+220=460>>460 carriages.
#### 460