This was very informative and does cover most of the situation on the manpower planning. I have some additional thoughts , is that is it not correct for the HR to understand the business of the organisation and from the perspective of the sales team to know what is the current market scenario of the products / service that is being offered by the company, what needs to be done to excel, clear understanding of the short comings or the goodness of the organisation from the sales front. As this would help the HR the ground reality, very few organisation have the sales HR position, going forward my view is that the HR should be involved in the sales figures and their forecast as that would empower the HR to take the right decision of the Manpower planning.

May make a suggestion is that we can create a HR meet with the help of CII or CMA, as this would help in lots of way.
I will see if it is possible for my organisation to participate and have a hour long seminar on HR services topic. as organisation need to be more focused on people or employee engagement, as that is the core activity of HR and Sales HR is another important aspect. The HR should be a brand ambassador for the organisation, as s/he is meeting future employees so s/he needs to sell the organisation to the candidate and has to present the facts about the organisation.
Some times if required for a particular position it is best for the candidate to go over the department and meet some of the employees to get a first hand knowledge of his coworkers.

Aparna, very simple method to be adopted but one needs to understand what is the type of organisation, locations, the industry the cater to, the years in business. As all this will help overall, do they have research executives or only recruiters, do they have BDM's ??

Well! just to give u a rough way of making an organisation structure would be
1. Recruiter to handle verticals like BFSI, IT/ITES/BPO, Auto manu/ancilarry, FMCG, FMCD, Retails, Agriculture, Engineering --- Electrical & Electronics, Energy,
Foundry,Aero, Plastics.etc, Pharma, Like this if you find a specialist recruiter, then u can have a TL/ Mngr etc. BDM's will be seperate set of people.

Let me know on my queries & I will help u