Workflow Task Approver Name

Hi,

I have a workflow which starts a task process when initiated.

I am looking to capture the name of the person from the "Holiday Request Approvers" group that approves the holiday request.

I have done a lot of searching and tried using [%Current Item:Modified By%] but this returns the name of the user making the initial request for the holiday and not the person who approved it.

I have come across some posts that contain [% CurrentTask:ModifiedBy %] but Current Task is not available from the drop down menu?

I am using Sharepoint Designer 2013 hosting on Office 365.

Any Ideas?

Cheers

James