the prior art as can be seen from fig3 where pin assembly 10 is shown in situ in a hatch 50 shown in dotted outline pin 12 may be provided with a circumferential notch 48 which can be gripped by suitable means such as teeth in the latching mechanism not shown it is optional to include a manual release with pin assembly 12 a manual release may be desirable in the case that locking pin 12 does not release from its corresponding aperture an embodiment of manual release is shown in the drawings especially with reference to fig1 it will be noted that guide pin 30 has base 31 which is circular in cross section base 31 can slide within base 32 as far as pin plate 14 but because of its circular cross sectional shape can travel no further towards locking pin 12 in normal use there will be a gap between base 31 and pin plate 14 when guide pin 30 is inserted in base 32 and locking pin 12 in normal use the leading point 51 of guide pin 30 will be wholly contained within locking pin 12 or will protrude to a small extent through aperture 52 in locking pin 12 u2014 especially when locking pin 12 is pressed back into housing 16 against the bias of spring 28 because of latch misalignment etc such small protrusion is insufficient to disengage the latch mechanism if it is necessary to manually disengage the latch mechanism a pick or other suitable tool can be inserted in a hole not shown located in well 17 of housing 16 to push on base 31 of guide pin.