How to remove tap cover?

Hi.
A complete novice here so any help much appreciated.
Got a dripping tap and [after trawling the net]am willing to have a go at replacing the washer.My problem is i cant remove the tap cover,there is no screws anywhere not under the hot/cold disks or the side of the tap.I have turned the main water supply off and totaly opened the tap.Is it a case of trying to 'force' open the taps further and removing the covers?Taps are,at least,20 years old and never been removed.
Thanks in advance.
Dave