Perplexing Ranking Oddity

[Simsi]

I have a US-hosted .com that has a number of products, 2 of which are particularly popular. For a couple of years, most of those products have ranked number 1 or 2 in Google.com and English-speaking local versions of Google around the world.

There is just one page per product and each ranks for both the singular and plural, both of which attract similar amounts of traffic.

About 4-5 months ago one of my popular product pages totally disappeared from UK SERPS for the singular term only. It still ranks no 2 for the plural and no other product pages were affected. It still ranks no 1 or 2 for the plural in all the other Googles. But in the UK, it's not even ranking for the singular term in the top 250 (which is as far as I've gone).

I'm perplexed as to why this might happen. Can anyone shed any light?

[brotherhood of LAN]

Two angles come to mind, not necessarily the reason why though.

1) Did you have any prominent backlinks from .uk sites that are no longer?
2) Any idea if the bounce rate was higher for UK based visitors?

Also it'd be good to know how you're deducing what the UK SERPs are, I find [google.co.uk...] without cookies to be the "vanilla" results.

[RedBar]

Can anyone shed any light?

Quite simply the Google.co.uk SERPs have been almost total garbage for months on end for some widget products, for many I see nothing but US .coms dominating the results when they clearly should not even be there and for other results I see hardly any UK .coms and nothing but .co.uk sites, some good, some bad.

Google really seems to have a big problem with their UK SERPs and they are, unbelievably, getting worse and worse...in my widget sector.

[JD_Toims]

It could be a linked phrase issue where the algo [that would be the portion we call Penguin] has determined the singular is linked too heavily relative to the whole of the phrases in links to the page -- Has it by chance been replaced by a different page on your site that might not even fit the query in a lower position somewhere in the top 40?

[Simsi]

1) Did you have any prominent backlinks from .uk sites that are no longer?
2) Any idea if the bounce rate was higher for UK based visitors?

1) Not that I can see
2) I'll check but I would have expected that to affect other terms if it was the case and no others have been touched.

Also it'd be good to know how you're deducing what the UK SERPs are, I find [google.co.uk...] without cookies to be the "vanilla" results.

[google.co.uk...]

I've also checked with webceo to be sure.

It could be a linked phrase issue where the algo [that would be the portion we call Penguin] has determined the singular is linked too heavily relative to the whole of the phrases in links to the page

That's an interesting one. External links don't really play a factor in this site's rankings but internally that may well be the case. However that said, would this not then apply in other Google versions like the .com?

The singular still ranks no 1 in .com, 5 months after the UK ranking was lost, so I'd be hesitant to make too many alterations to the structure at this point.

Has it by chance been replaced by a different page on your site that might not even fit the query in a lower position somewhere in the top 40?

Doesn't appear to be the case.