Steve -
just a word of advice: apologies if you already know this!
there are two types of record on the IGI. One is Extracted, the other is Submitted. The note at the bottom states which it is.
Extracted entries are - in the main - taken from the original record and are fairly reliable (although you should always try and see the original for confirmation)
Submitted entries are (usually) from other researchers and are far, far less reliable. They often do have correct dates for one or more of the events on the record, but from that they go off in a spin sometimes (more often than not, I'm afraid)
A hypothetical example:
John Smith married Jane Brown 23 Sept 1790 in Portsmouth.
That bit might be quite correct.
Then, there might be the assumption that John married aged 20, so they say
John Smith born about 1770 (about is the watch-it! word) and Jane was younger so they say Jane Brown born about 1772. Then, they assume that having married in Portsmouth they came from there, and put "of Portsmouth" (of is the other watch-it word)
In fact, John was in the Navy and came from Okehampton in Devon and was born in 1760, and Jane was only working in Portsmouth, she was born in Winchester and was 3 years older than John. But someone may spend years looking for John Smith born 1770 Portsmouth!
Secondly, - on a site called Genuki there is a list of the registration districts and the places each one covers, which you might find useful if you haven't already found it.
