Hi Donna......
British stamps always show a portrait of the Queen.....colonies show both the portrait and the name of the colony.
There are 3 identical looking stamps like this. You need to soak the stamp face down in cold water until the backing paper floats off and you should be able to see the water mark.....if not let it dry face down then place it on black or very dark paper (or anything dark) and the watermark should be fairly clear. This works for most British & British colony stamps.
The stamp is Great Britain #309, wm308, 1955, $2.25........ #371, wm322, 1959, 45cents.........or.......#525 with no watermark, 1968, 50cents..

Any stamps you intend to keep should be soaked to remove any extra paper. 98% of all pre-1975 stamps will soak cleanly in cold tap water.