Hi Kerry
Oops. I've just looked again at the IGI, and it turns out I was not quite accurate. I'm seeing two different records on the IGI.
There is a christening record for MAHALATH CHANTLER, 10th July 1803 Barcombe Sussex. Her parents are given as EDWARD CHANTLER and SARAH. There is a birth record for MAHALA CHANDLER, about 1807, Barcombe Sussex. No parents, but husband is WILLIAM MUGGRIDGE, with two children WILLIAM and JAMES.
The second record is certainly my MAHALA, but if you overlook the four year difference the two records are not actually contradictory. Census mentions in '51, '61 and '71 give my MAHALA's age as 44, 53 and 63 respectively, which ties in pretty closely with a birth year of 1807.
I'll certainly look a bit closely at EDWARD and SARAH now as a possibility.
I'm actually in central Victoria, in Australia, so reaching the Lewes Record Office is fairly difficult! I'll check out the site you suggested though.
Thanks again
Alan Muggridge