Step 1: Concept Analysis:
Using the deductions from the passage, identify the Lawyer's colour.
Step 2: Solution Approach:
The friend who likes Blue is either a Lawyer or cleans on Saturday. The Saturday person is the Hotelier, not the Lawyer. Therefore, the Blue-liker must be the Lawyer (since if Blue-liker cleaned on Saturday, they would be Hotelier, not Lawyer -- contradiction if the Lawyer doesn't clean on Saturday). Hence, the Lawyer likes Blue.
Step 3: Conclusion:
The Lawyer's favourite colour is Blue.