Good news! The 1100 being such a great car (not like the vastly inferior mini) you can remove the rack without removing the subframe....
What the BMC book says.....
Quote:
Section J.3
Steering Rack and Pinion
Removing
Remove the steering column as described in section J.2
Jack up the car beneath the front sub-frame and remove both front road wheels.
Disconnect the steering tie-rod ball joints.
Support the engine with lifting equipment from above or with a variable-height trolly jack under the transmission casing.
Remove the set screws and bolts from the six sub-frame mounting points.
Remove from inside the car the nuts from the "U" bolts screwing the rack housing to the toeboard.
Lower the engine just far enough to permit the rack assembly to be released from the toeboard and withdrawn from the drivers side of the vehicle.
NOTE.- The suspension displacer hoses, hydraulic hoses, controls, etc. have not been disconnected for this operation, and to avoid damaging them the engine must not be lowered more than is absolutely necessary.
Now what I have found is that with most cars you can remove the rack without touching the subframe at all.
You undo the rack and rotate it to get the pinion through the floor and slide it out the side.
If it will not come out just undo the subframe bolts a little (not all the way) and then try again.
Unless it is an very early car (1100S should be late enough) the rack should use the same bushes as the Australian mini rack.