If you wish to register your support or your objection to the proposed change of use for the Spar shop, then your comments need to be submitted by this Friday (June 13).
This can be done by post or by e-mail. In both instances, you should quote the Application ID: NP/DDD/0408/0307.
E-mails should be sent to planning.service@peakdistrict.gov.uk.
Letters should be sent to: Peak District National Park Authority, Aldern House, Baslow Road, Bakewell, Derbyshire DE45 1AE.
To quote from the PDNPA’s guidelines:
Please be aware that by law, letters and emails received in relation to planning applications become public documents once we receive them.
By law we can only take account of policies and material planning considerations such as:
- Compliance with national and local policies
- Design and appearance of the development
- Impact on neighbouring property – loss of amenity, privacy or unreasonable scale
- Environmental impacts
- Traffic impacts
The law states we cannot take account of non-planning matters such as loss of view, devaluation of property or character of the applicant.
PARWICH.ORG 
As Jazz pointed out, the relevant local policy here, is:
Peak District National Park – Local plan adopted 2001
Shops, Services & Community Facilities
5.6
Changing a shop to another use is resisted by Structure Plan Policy SC1. This protects the availability of facilities locally, and in particular helps the young, the elderly and those without access to private transport. It can therefore encourage a more sustainable transport pattern. Only where it can be shown that a shop is no longer viable or required by the local community, and that the proposed new use meets another community need, should change of use be allowed. In determining whether change of use will be allowed, the National Park Authority should therefore consider why the application has been made, the importance of the outlet to the local community and whether reasonable efforts have been made to continue the use if still viable. Where it is accepted that the present use is unable to continue, the approved new use should provide for another local community need, such as affordable housing or workspace. However, where an existing shop is operated from part of a family home, residential amenity may sometimes override other considerations. The General Permitted Development Order 1995 allows for the change of use of the first floor of a shop to living accommodation or a financial or professional service use without the need for Planning Permission. Such uses can prevent the loss of vitality that accompanies buildings, which are partly unused. The National Park Authority will encourage the appropriate use of upper floors of buildings when assessing development proposals.
http://www.peakdistrict.org/chapter5.htm