You probably know but the :
No7 Mk1 was ordered by the RAF. Apparently 2500 were ordered and some 2000 (ish) supplied with the remaining (un assembled) actions being sold off. A few went to the USAand Brian Dick
acquired some and had the bolt head and ejectors manufactured locally.
No 9 is also marked as N9 Some 3,000 were ordered from PH for the Navy
Production commenced in 1956, although we have yet to see a rifle dated prior to 1957, (i.e. P-H 57 as above). Of the 3,000 or so rifles apparently manufactured for the Royal Navy contract between 1956 and 1960, the serial numbers did not attain four figures until during 1958, and were marked as the Pattern Room example and the example shown above. The highest "A" prefixed number of which we are aware is A2828 - a rifle sold at Bonhams London auction in 2004. Later rifles produced by Parker-Hale had the markings engraved, as on the rifle shown higher up this page, and the serial numbers became five-figured with the prefix "PH". We have no information regarding the quantity of these rifles marketed, there being no information readily available relating to serial numbering. It is known that later 'reproductions' of the No.9 were produced by a well-known gunsmith in Birmingham in the late 1990s, using various spares. These too were produced with the usual beechwood furniture, and are very difficult to tell apart from rifles of original commercial manufacture.; indeed, even the PARKERIFLING marking was included on the barrel's crown. Whether or not the barrel carries modern proof, normally under the front section of the barrel ahead of the fore-end nose piece, could be a give-away here. Original rifles should also be fitted with the alloy butt-plate.
The Pattern Room collection's rifle is presumed to be a mid-production example marked "N." for Navy, whilst those later production rifles with the PH serial number prefix had this transposed to "No." and the markings, as shown on the rifle on this page, were engraved rather than stamped. That these rifles were notated "9" is something on which the reader may muse, particularly with regard to discussion above about Britishor Enfield Rifle
numbering.
https://www.rifleman.org.uk/Enfield_Rifle_No.9.html