Without an independent medical examination very difficult to give a figure as it can be anywhere between Â?1,000 and Â?7,500 + depending on the severity, and that is providing a full recovery has been made and there are no underlying problems.
Special damages cover the injury and then there are General damages which cover all out of pocket expenses, pain and suffering damaged property and so on.
They are trying shortcut the system so as to undervalue the claims and also save themselves third party costs.
I would really advise you speaking to either a local personal injury solicitor or your insurance company for your own protection as well as your sons.