chipg and watermark - very nice stamps !!
I honestly have alot of these stamps. Now I'm sure that there are many collectors who have more than me. But it's pretty hard for me to pick out a few of these to show but I'll give it a go.
1c E Flaw - Ex Geoffrey Whitworth

5c Thick Paper (dare I say) Jumbo

5c MLH - VGG Cert

10c Unused (No Gum)

10c Unused String of Pearls (Late Printing has extra flaw near POS of POSTAGE)

12 1/2c Horizontal Stitch Watermark (Cert)

12 1/2c VF Used on cover to Glasgow

17c Mint Light Hinge Full OG VGG Cert

2c (left to right) Claret Mint, Rose Mint, Rose Used Large Margins.

Now you know why there are so few of them out there that are well centered ... because we bought them all ! :-)