Giant

Waddington’s started their Giant 439 piece jigsaw range in the 1930’s. On the boxes they boasted that ‘The size of this puzzle is the largest on the market, being 21” x 15” ‘. They came in boxes printed in yellow and red to look like a leather bound book and the early ones had the volume number and title on the spine. The boxes were 8” x 12” x 1 1/2” initially, later ones were 11” high. They were priced at 1/-, although later ones were 1/3. Subjects were either contemporary (Winter Glory, the Finish of the Derby), film scenes (Lady Jane Grey, The Prisoner of Zenda, Under Two Flags, As You Like It), historical ( King Alfred and the Cakes) or the bucolic ideal, idealised scenes of country life ( Gypsy Joy, Halt at the Smithy, the Toddler’s Return, Sheep Dipping).

Later puzzles (after no. 78) were packed in smaller square boxes with an "Up to the Minute" logo and the price increased to 1/6 after purchase tax was introduced in 1941.

See also the Interlock range, which came in matching packaging but were presented in a smaller format.
Many thanks to Jerry Mortimore for supplying the details and first examples of some of the large number of puzzles in this range.