A method of forming a seal between two housing parts, at least a first one of which comprises a channel shaped portion; the method comprising: i) providing a sealing member that prior to sealing has a transverse dimension that is greater than a transverse dimension of the channel shaped portion; ii) positioning the sealing member adjacent to the channel shaped portion; and iii) moving the second housing part relative to the channel shaped portion, causing the sealing member to be inserted into the channel shaped portion of the first housing part, and thereby compressed in its transverse dimension.
