M1 Garand Lend-Lease: Understanding Matching Numbers & Value

Question
Sir,
I am new to gun collecting,
I have found an M1 Garand British lend lease.
I am wondering if it is an issue if the numbers do not match on the gun.
Is this common, does it take away from the value and collectibility of the rifle?

Thanks.

Answer
Matching numbers raises the value. Few of them still have them as most have been refurbed at least once.
Here what one should look like marking wise.
http://forums.gunboards.com/showthread.php?231154-WTS-WW2-Springfield-Armory-8-1
It also could could have assembled out of mixed parts.
You should have a gunsmith look at it before you buy.