Great Britain SG#LP50 4/6d- Black on Grey Blue 1967-1971 Pre-Decimal Machin Heads Issue, A Complete Booklet From March 1969, Various Fluorescence Levels For Interleaving Pages (Combination B), Medium Fluorescent "Sirius" Cover

A well centered, very fine and fresh example of this 4/6d booklet from the 1967-1971 Pre-Decimal Machin Head Issue. The contents have the following characteristics:

Paper type: Vertical wove paper, chalk surfaced and giving a high fluorescent reaction on the front, and a high fluorescent flecked reaction or high fluorescent reaction under UV on the back (HF/HF-fl) or (HF/HF). The 4d panes are horizontally ribbed

Printing method: Photogravure

Rate page features: March 1969 date on bottom right of page.

Printer: Harrison and Sons

Perforation or die cut: 15 x 14 comb (Type I)

Stamp colours: 4d vermillion, and 1d yellow olive.

Gum Type: streaky cream PVA with an satin sheen on all panes

Head Type: Head B

Phosphor: 2 side bands, clearly visible on the 1d and clearly visible centre band on the 4d

The covers display the following characteristics:

Cover fluorescence: Medium fluorescent on front and back

Cover seal type: unsealed

Cover design: Sirius

Cover binding type: stitched with black thread

Interleaving inside? Yes, 5 double sided pages of text, giving different fluorescent reactions under UV as follows:

• Page 1 - medium fluorescent
• Page 2 - medium fluorescent
• Page 3 - medium fluorescent
• Page 4 - dull fluorescent
• Page 5 - dull fluorescent

The scans show a sample of the pages from a similar booklet. The specific adverts will be different for different booklets, but this gives you an idea of what they generally look like.

Cover Colours: Grey blue with black printing

Counting mark on cover?: No

The Gibbons catalogue value for a F-65 mint example of this booklet is £2. This translates to $4. The booklet offered here grades VF-77 as follows:

Cover freshness: 10/10

Centering of the panes: 50/70 (average of both panes)

Condition of cover edges: 5/5

Freshness of the panes: 5/5

Absence of visible cover flaws or stains: 5/5

Condition of interleaving and contents: 2/5 (perfs trimmed along one edge of all panes).

The white chalk-coated papers of the panes do exhibit variations under long-wave ultraviolet light. Generally they vary from high fluorescent to hibrite. These differences can be seen from the front of the stamps, but are most dramatic when viewed from the back of the stamps. The attached scan shows just how dramatic these differences can be.

In addition to visible and noticeable variations in colour shades in normal light, many of the values in the set show clear differences in the composition of the printing ink when viewed under UV light, with some stamps appearing to be a darker version of their issued colour under UV, some appearing to be a much lighter colour, and others appearing to be a different colour entirely.

The bust of the Queen varies between printings also. Head A has a relatively flat bottom to the bust, whereas Head B has an extra curve added at the base that makes it look rounded. These two types are found on most of the values, though a few are only found with Head C, which is similar to Head B, but with a more three dimensional effect.

In addition to the listed gum differences of PVA and gum Arabic, the PVA gum can also be found in smooth and streaky versions.

The perforators used also vary, and the differences lie in whether the vertical perforations extend into the selvage:

• Type I - vertical perforations do not extend into the selvage, so that selvage is fully imperforate at the vertical sides.
• Type I(1/2v) - as above, but one corner of the selvage is skimmed off.
• Type AP - Side perfs extend all the way through the selvage, but the middle row of perforations do not.
• Type P - all perforations extend all the way through the selvage.

Finally the phosphor bands can be found in different strengths ranging from very obvious to the naked eye to almost invisible to the naked eye. Also, there are the listed variations in band orientation, such as 2 side bands, one centre band, 1 side band, etc.