  We study a classical ferromagnetic Heisenberg model in the presence of
Dzyaloshinskii-Moriya interactions on the corner-shared triangle lattice formed
by the Mn sites of MnSi. We show that a sizable spin helicity can be obtained
only when the microscopic Moriya vectors lie parallel to the Mn-Mn bonds.
Further, such vectors are shown to produce an unpinned helical order
characterized by a particular ordering wavevector magnitude but unpinned
direction, dubbed partial order, at physically realizable temperatures. A
consequence of such an unpinned helical ordering is that the neutron scattering
intensity is sharply peaked at this wavevector magnitude. The surface formed by
connecting these wavevectors is a sphere, around which the neutron scattering
weight is spread. We further show that the observed neutron scattering
intensity can be anisotropic along this surface and that this anisotropy is
dependent on the experimentalist's choice of lattice Bragg peak through a
geometric factor. A neutron scattering measurement near the Bragg point
($\frac{2\pi}{a}$,$\frac{2\pi}{a}$,0) naturally leads to a highest intensity
along the (1,1,0) direction consistent with the observed anisotropy in MnSi
[Pfleiderer {\it{et al.}} Nature {\bf{427}} 227 (2004)]. A possible mechanism
for pinning the helical order, and a way to distinguish an ordered and a
partially ordered state in the context of neutron scattering are discussed.
