It comes from a book i got off ebay titled River Tyne Official Handbook which comes from around that time. Hardback book with 125 pages full adverts, info and pictures.
You now need to look for the 1925, 1930 and 1934 Edition.
My 1934 Handbook has Third Edition 1934 on the Front so the one you have must be the Fourth Edition. There are different pictures of Tyne Dock in the first three editions.
Don't know where I got this fact from now, but "at its height in 1913, 7 million tons of coal were exported from Tyne Dock and in the period between 1859 and 1934 it had shipped a total of 323 million tons. Imports were also handled at the dock and iron ore, pit props and sawn timber were all unloaded"