Thank you all for various replies.
Undercarriage hand pump: I also had other correspondence suggesting Walrus.
Fuel tank: This is cylindrical and is definitely not from a Lancaster anyway.
Mark’s questions: The fuel tank is steel, whereas the radiator fluid tank seems to be bronze or similar. I had assumed the latter was aircraft because it is somewhat aerodynamic in cross section. I thought it might fit on the style radiator that protrudes from the side of the fuselage, like the radiator on the Armstrong Whitworth F.K.8. The ‘cut-out’ in the tank is ‘gloved-hand’ in size, so I thought that would provide clearance for a hand-hold.