First one I played...that would be one of those Aristocrat Bar X O one armed bandits [I believe they were made by Aristocrat].
2p Play [only coin it accepted], 20p for 3 Xs and I think £2 for 3 Bars [although it paid out the £2 in the forum of 2ps, 10ps and 20ps :S]
Probably about 6 when I used to play that at Thompsons arcade in Bridlington. In the same arcade I used to play :
1) A Rifle Range machine, think it was 20p ago, and I never won the JP [whatever that was, probably a quid!].
2) A Bubblegum machine, I remember there was a glass cabinet, a tube full of bubble gum, and you had a joystick with a fire button. I think you had to hit a moving submarine or something?
3) Tooty Fruity, a machine with about 4 slots at the top, and the coins [2p on the one I played] would fall down a panel behind a pane of glass with several fruits in it [in the form of metal discs with lights in I think]. When the coin hit a disc, it lit it up. I think you had to light up 3 fruits in a row and you got something like 10p as a prize? [The fruits were probably in rows of 4, although I can't remember

]
Hours of fun for a bag of 2ps