An airframe by itself is no good without engines. In the case of the Lancaster (and many other front line British aircraft) that engine was some variant of the Rolls Royce Merlin. (Note: The name did not come from the magician from the legends of King Arthur as many think. A Merlin is also a small species of falcon found in North America and Eurasia. Most Rolls Royce engines of the time used a birds of prey naming convention.)

The Merlin was a V12 piston engine. It had a capacity of 27 litres (1,650 cu in), and was liquid cooled.

Here, we see the cowling off which allows us to get at least a partial glimpse inside the workings of the engine.

As I mentioned in a previous image this is actually a Lancaster Mk VII which is impersonating a Lancaster Mk I. The real Lancaster Is generally used the Merlin XX engine which produced 954 kW (1280hp) at 3,000 RPM. (Some used the 22 model.)

A Lancaster VII, however, used a Merlin 24, which generated 1,201 kW (1,610 hp) at 3,000 RPM. Presumably this is the latter model, though it's academic since this Lanc is unlikely to be flying anywhere soon.

Both types, as far as I have been able to determine, used a 3 blade De Haviland variable pitch, constant speed propeller as shown here.

(A constant speed propeller automatically changes its blade pitch (roughly the angle between the blade and the rotation of the propeller) to allow it to maintain constant revs per minute regardless of engine torque, airspeed or altitude. It makes for more efficient flying.)

Addendum: My personal opinion is that Facebook is a sociopathic organisation that steals other peoples' intellectual property (including the images in this gallery) despite being explicitly denied permission to do so.