Pooh, Your stamp is part of the Birds Heads issue of 12th June 1974. It is a set of three and numbered as Stanley Gibbons SG.270-272. Your individual stamp is catalogued at 70 pence British.Yours has a nice postmark.
The Scott number for your stamp is 400. According to the 2017 Scott catalog, the value is $3.25 in used condition.
Looks like the stamp has toning on the perfs. That will pretty much negate any value.
Being toned and used, no gum obviously, put in water and bought to the boil, boil and watch, dry out, toning gone.
Could someone please tell me about this stamp I haven't seen this at any auctions One stamp person told me it is worth about $5.00
