Hello,
This is because of the prefix/suffix area. The area where the elements are transitioned is called the prefix/suffix area and its size is set to a default percentage (15%) of the whole path. Please note that the value can be between (0.0 and 0.4). If you want to reduce the size of the prefix/suffix area, you can use the ItemPathPrefixPercent and ItemPathSuffixPercent properties:

ItemPathPrefixPercent="0.05" ItemPathSuffixPercent="0.05"

Thanks Alex. Thats what I needed.

Just one last problem. The items running across the top of my path are shoulder to shoulder, whilst there is some padding down left and right of the path.

Is there something more I could do? I have attached the xaml

<igDP:XamDataCarousel x:Name="xamDataCarousel1" 
                                      Margin="0,-50,0,0"
                                      Theme="Water"                                                      
                                      HorizontalAlignment="Stretch"    
                                      VerticalAlignment="Stretch"
                                      Width="Auto"
                                      Height="450"
                                      GroupByAreaLocation="None" >
                                    <igDP:XamDataCarousel.FieldSettings>
                                        <igDP:FieldSettings AllowRecordFiltering="True" CellClickAction="SelectRecord" AllowEdit="False"  />
                                    </igDP:XamDataCarousel.FieldSettings>
                                    <igDP:XamDataCarousel.ViewSettings>
                                        <igWindows:CarouselViewSettings
                                          ItemPathStretch="Uniform"
                                          UseScaling="True"                                           
                                          IsListContinuous="True"
                                          ItemPath="{StaticResource SquarePath}"
                                          ItemsPerPage="20"                                
                                          UseOpacity="True"
                                          ItemPathPadding="0"                                       
                                          ItemSize="125,75"
                                          ItemPathPrefixPercent="0.001"
                                          ItemPathSuffixPercent="0.001" >
                                        </igWindows:CarouselViewSettings>
                                    </igDP:XamDataCarousel.ViewSettings>
                                    <igDP:XamDataCarousel.FieldLayoutSettings>
                                        <igDP:FieldLayoutSettings AutoGenerateFields="False"  />
                                    </igDP:XamDataCarousel.FieldLayoutSettings>
                                    <igDP:XamDataCarousel.FieldLayouts>
                                        <igDP:FieldLayout Key="PATNT_PASID">
                                            <igDP:FieldLayout.Fields>
                                                <igDP:Field Name="Brief" Label="Brief" >
                                                    <igDP:Field.Settings>
                                                        <igDP:FieldSettings CellMinWidth="50" CellWidth="50" CellHeight="20"  />
                                                    </igDP:Field.Settings>
                                                </igDP:Field>
                                                <igDP:Field Name="Name" Label="Name">
                                                    <igDP:Field.Settings>
                                                        <igDP:FieldSettings CellMinWidth="50" CellWidth="50" CellHeight="20"  />
                                                    </igDP:Field.Settings>
                                                </igDP:Field>
                                                <igDP:UnboundField Name="UserImage" Label="UserImage">
                                                    <igDP:UnboundField.Settings>
                                                        <igDP:FieldSettings CellMinWidth="20" CellWidth="20"
                                     CellValuePresenterStyle="{StaticResource UserImage1}" />
                                                    </igDP:UnboundField.Settings>
                                                </igDP:UnboundField>
                                                <igDP:Field Name="CareUnit" Label="CareUnit" Visibility="Hidden"  />
                                                <igDP:Field Name="PATNT_PASID" Label="PATNT_PASID" Visibility="Hidden"  />
                                            </igDP:FieldLayout.Fields>
                                        </igDP:FieldLayout>
                                    </igDP:XamDataCarousel.FieldLayouts>
                                </igDP:XamDataCarousel>

I believe there is no way to control how the items are positioned along the path. They are aligned along the path in equal offsets based on the items per page property so that the whole path is occupied. Some empty spaces could appear depending on the width or height of the items and the path.