Box containing technical records - One folder for Yard No. 593, one booklet for Yard No. 728 'HMS Undine', three booklets for Yard No. 729 'HMS Unity', three booklets for Yard No. 730 'HMS Ursula', one booklet for Yard No. 745 'HMS Tetrarch', one envelope for Yard No. 758 'HMS Upright', one booklet for P31-P39 & P41, one folder for 'L' class submarines. One folder of both technical records and ship plans for Yard Nos. 768, 769, 787, 788 & 827.