I forgot to mention that of course all vowels are voiced, which explains why speed and weed both end with a voiced consonant 'd' - since the vowel preceeding - /i:/ - is voiced (/i:/ sounds like 'ee' in sheep).
Past perfect is used in literature (and speech!) to fill in the background to events, to give a 'flashback' effect so to speak. It is the 'past before the past' so to speak. But that could be ten minutes, or ten millennia ago.
'Perfect' (derived from latin) translates into English as something like 'up to / before' hence present perfect refers to the period of time 'up to / before the present' while past perfect refers to the period 'up to / before the past'. All perfect forms imply a period of time over which there is no change in the situation or action of interest to us. Change in the past perfect is indicated using past simple:
"I had lived in London for 10 years before I MOVED to Paris"
note that the clause "I had lived in London for 10 years" can't stand on its own, as it assumed that something else must have followed this action.
Several languages (e.g French, Spanish and Italian) have forms similar to English perfect forms but are used differently: "io ho visto ieri" in Italian literally translates as "I have seen him yesterday" but obviously you can't use present perfect with past time expressions like 'yesterday' so the correct version in English would be "I saw him yesterday" just using past simple. On the other hand those languages also have different forms of the past for near or far off actions:
Ho avuto una macchina (I had a car, yesterday, last year)
Avevo una macchina (I had a car when I was 16)
English doesn't have that kind of remote past. The past perfect doesn't really perform that function as it simply refers to a period of time before a point in the past, which is uually connected in some way to that past event.
BTW, does this constitute thread drift?
That got me to thinking, I'm off to start a thread on the best grammatical / spelling howlers you've seen while out and about, or in books.