Bad news for roots vinyl collectors

There's more bad news for collectors of original 50s and 60s vinyl in the newly published Record Collector Rare Record Guide (the 2016 edition no less). Prices of many rock and roll and pop records from that time have been tumbling for several years and the latest guide shows a continuation of that trend. Meanwhile, values for progressive rock, psychedelic, some reggae, jazz  and punk, and Northern soul have held up or increased. The revival of  vinyl in the form of reissues and new product doesn't seem to have affected the values of original collectables that much, so far as I can see.
The gradual decline in values of original rock and roll records is vividly illustrated by Joe Bennett and the Sparkletones' two HMV 45s from 1957 which have declined from a peak of £250 each for mint copies  in the 2006 edition to £100 in the latest book. Unfashionable artists such as Brook Benton, Brenda Lee and Connie Francis have seen a drastic reduction in the number of their records making the list at all, not helped by the decision to increase the lowest value for LPs in the book from £12 to £15. Only one 45 by Brook Benton now qualifies for an entry (plus two with Dinah Washington).
Meanwhile there have been dramatic increases in values for other artists. The first pressing of Led Zeppelin I now weighs in at £1500, compared with £500 in 2006. First pressings of the sought after stereo version of the Beatles' Please Please Me LP has doubled to £6000. Interestingly the book is still the same size, but it is now bunged up with valuations of minor variations of promo records by more modern bands such as the Manic Street Preachers and Radiohead.
I'm sure a close inspection of my own collection would show quite a steep drop in the overall values. But there's some good news for some of the records that I've acquired over the years which I thought might be worthwhile investments. My most valuable LP is the Parlophone LP We Are Everything You See by Locomotive which now comes in at £1000, compared with just £200 in 2006. Most valuable 45 appears to be the pre-Who Zoot Suit by the High Numbers, which is also now rated a £1000 disc, compared with £350 in 2006. I continue my searches at car boot sales and charity shops and who knows what might turn up!