This is clearly hung in a room off the Long Gallery, not in the Long Gallery itself

Van der Doort c.1639

Guido Reni

Judith cutting the head of Holofernes

Walpole Society reference (1960): 
WS 61, № 103
Measurements (Van der Doort): 
3ft 5in x 5ft 0in (104.1 x 152.4cm)
18th of the 23 Italian collection pictures the King bought from William Frizell
Gift / Exchange / Bought / Inherited: 
Hang notes: 
in the Duchess of Chevreuse's Lodgings over the Chimney, during the time of her abode here (at the present time)
Room description extended: 
towards the Orchard
Original Manuscript page number: 
MS. Ash. 1514, f. 83 and V&A MS f. 9, no 2 (WS 203)
Identification certainty: 
Sale Inventory c.1649-51

Guido Reni