Google ranking is much better for 'plural' searches?

we launched our new website a week ago and within 24 hours were getting decent Google rankings for a great deal of our content.



however, with more generic terms I can't understand why we get much better results for 'plural' search terms over singular…?



eg searches for Railway DVDs, Train DVDs, Rail DVDs will all give us top 3 rankings - but if you remove the 's' from any of the search terms (to give Railway DVD, Train DVD, Rail DVD) - then we are much lower - usually on page 2 of the results?



Anyone else had this experience?



We've used both singular and plural terms in our text, keywords, meta-descriptions… and yet 'singular' searches all give lower rankings than 'plural'…



???

Probably because fewer of your competitors use the plural terms in the content.

I always search google by the plural form. Not that this is of any use but seems logical to me.



Stu