Thanks for taking the time Stefan. Don't forget that in C = is an assignation, not a comparison, so the line

while ((*i2c_buffer = *str)!='O') //Finally I realised I should use a O instead of a 0 while posting here - sadly still no backslash

assigns the value pointed to by str to the address pointed to by i2c_buffer, then compares the value to 'O' and returns true if they are not equal.

I finally fixed it (I think) like this.

void send_i2c_data
	(
	unsigned char *str
	)

{
    unsigned char i2c_status;
    unsigned char idata *p_i2c_buffer = &i2c_buffer;

		while ((*p_i2c_buffer = *str)!='O')
		{
		str++;
		p_i2c_buffer++;
		buffer_count++;
		}
	
	i2c_status = i2c_transmit(0x60); //To be used later on when this function is expanded


}
 

i2c_buffer is declared earlier as

unsigned char idata i2c_buffer[20];