positive or negative earth??? help

[2011dandd]

Hi I'm in a bit of a pickle, please help

last week I bought a 1969 minor 1000, the first thing I need to get is a battery.
Am I right in thinking that this would have been positive earthed originally? so the positive battery terminal would be earthed to the car?
The previous owner has fitted an alternator so is it most likely that its now negatively earthed? I have really confused myself. With the bonnet open standing at the front of the car steering wheel on my lefty (right hand drive car) the negative strap/lead in the car is on the passenger side of the battery tray and is fixed to the body so am I right in thinking that this is the earth and that the car is negative earthed? on buying and fitting the battery this is what will connect to the negative battery terminal?
I know I have typed it out like a tongue twister but if anyone can make any sense of the above and offer some advice I would be very grateful for the help.
thanks

Dan

[minijojo]

the negativ terminal of the battery has lower diameter then the positiv terminal
if you buy a new one, look at the location of the terminals and the main dimensions of the battery

[les]

Originally positive earth but with accessories being negative earth nowadays, a lot of Minors have been swapped to negative. In which case the negative terminal on the battery. (-) is connected to the bodywork of the car (earth)

[Trickydicky]

As les says the negative side of the battery is the earth.
In laymans terms the battery has a positive terminal marked with a + (plus) sign and a negative - (marked with a minus sign).

[myoldjalopy]

It would have been positive earth orginally, as stated above. But the presence of an alternator confirms it has been converted to negative earth. So the negative terminal on the battery will need to be connected to the earth lead which connects to the car body.