The units at Heraklion at the time of the German attack on 20 May 1941

Volume II of the Australian Official History has a note on page 280 that gives the details of the force defending Heraklion at the time of the German attack on 20 May 1941:

Headquarters, 14th Infantry Brigade
2/Blackwatch with 867 officers and men
2/York and Lancasters with 742 officers and men
2/Leicester with 637 officers and men
2/4th Australian Bzttalion with about 550 officers and men
7th Medium Regiment with about 450 officers and men armed as infantry
a detachment from the 3rd Hussars with six light tanks (apparently Lt.Mk.VIb tanks)
a squadron from the 7th RTR with two infantry tanks (probably Inf.Mk.II)
234 Medium Battery with 13 field guns
two troops of the 7th Australian Light Anti-Aircraft Battery with eight 40mm Bofors AA guns
one troop of 156 Light Anti-Aircraft Battery with four 40mm Bofors AA guns
two sections of C Heavy Anti-Aircraft Battery with four 3 inch AA guns with some 2pdr AA guns
a section from 42 Field Company, Royal Engineers
a detachment from 189 Field Ambulance
one Greek garrison battalion
3rd Greek Recruit Battalion
7th Greek Recruit Battalion