If the lease gave you the option of which you could apply for in different circumstances which would you choose and why?

Scenario

Work individually, acting as an Independent Expert, and you should have regard to the RICS Practice Statement and Guidance for surveyors acting as Independent Experts. You should provide a suitable signed statement of truth as part of your work.
You need to assume that you have been approached in connection with the following rent review provision (see 15 below) to provide a view on the following matters:

If the rent first reserved is £50,000p.a; the rent immediately before the date of rent review £50,000p.a and the Market Rent £45,000p.a then what will the rent be following the rent review?

If the rent first reserved is £60,000p.a; the rent immediately before the date of the rent review £60,000p.a and the Market Rent £67,500 p.a. then what will be the rent following the rent review?

Set out how you would (in some detail with examples, created if necessary) arrive at a Valuation as per 15(3) – and comment as to the importance and meaning/impact of each of the provisions at 15(4). Here it would be helpful for you to find office comparables or available property of a similar size to the suite here, and use these in your work.
Finally, assuming that you are appointed to act for one party or another and the matter of determining a revised rent actually proceeds to third party explain fully the differences between that party acting as an Arbitrator and that party acting as an Independent Expert.

If the lease gave you the option of which you could apply for in different circumstances which would you choose and why?