The only wood-drilling spade bits B&Q seem to sell now is new threaded
ones (can't remember the manufacturer). The pointed end is threaded
and the pack says (quicker cutting blah blah).
They are useless. The thread pulls the bit into the wood so rapidly
and in a totally uncontrolled way, where it promptly gets jammed and
tears up the wood before yanking the drill out of your hands. Who ever
designed these clearly tested them only on cheese. Very strange.
Simon.

The thread pulls the bit into the wood so rapidly

Option-1
o Use the bit with a very high torque drill set to run very slowly

Option-2
o Disable the drill self-propulsion by drilling a hole through
o Hole prevents the drill's threaded tip pulling the bit through
o Instead you will have to provide a little pressure yourself

Self-propelled auger bits are commonly used with manual
brace-n-bit hand drills. In that situation the self-propelling
capability helps - and speed is very low. Copying the idea
for a flat spade bit seems a little extreme - the drill will flail.

Flipside is self-propelled wood bits are vastly quicker than
holesaw - but require high torque drills ideally with a gearbox.
Not difficult to improve the common holesaw for wood, after
a short distance poor debris evacuation allows teeth to block.
--
DB.