Table:
text: List of Great Central Railway locomotives and rolling stock
Coaching stock
British Railways Mark 1 coaches
Number_Name Description Livery Owners Date_
No. E3079 Mark 1 FO BR Blood and Custard . Great Central Railway Plc. 1956
No. SC4207 Mark 1 TSO N/A. Great Central Railway (Nottingham) Ltd. 1956
No. E4630 Mark 1 TSO BR Blood and Custard . Great Central Railway Plc. 1956
No. E9316 Mark 1 BSO BR Lined Maroon . Great Central Railway Plc. 1956
No. E15960 Mark 1 CK BR Blood and Custard . Private Owner. 1956
No. 34990 Mark 1 BSK Departmental Yellow & Black. Private Owner. 1956
No. W80438 Mark 1 POS Royal Mail (1960s) . Railway Vehicle Preservations Ltd. Private owner. 1956
No. ADB975638 Mark 1 BSK N/A. Private Owner. 1956

text: List of Great Central Railway locomotives and rolling stock
Coaching stock
British Railways Mark 1 coaches
Number_Name Description Livery Owners Date_
No. S4830 Mark 1 TSO BR Green . Great Central Railway Plc. 1959
No. E4857 Mark 1 TSO BR Blood and Custard . Private owner. 1959
No. E16070 Mark 1 CK BR Lined Maroon . Private owner. 1959
No. W80301 Mark 1 POS Royal Mail (1960s) . Railway Vehicle Preservations Ltd. 1959
No. 80307 Mark 1 POS Royal Mail . Private owner. 1959
No. 80401 Mark 1 POT Royal Mail (1960s) . Private owner. 1959
No. 86709 Mark 1 GUV Maroon. Private owner. 1959
No. 86830 Mark 1 GUV Maroon. Private owner. 1959
No. E93565 Mark 1 GUV BR Rail Blue . Great Central Railway (Nottingham) Ltd. 1959

text: List of Great Central Railway locomotives and rolling stock
Coaching stock
British Railways Mark 1 coaches
Number_Name Description Livery Owners Date_
No. S14026 Mark 1 BFK BR Green . Great Central Railway Plc. 1963
No. W80458 Mark 1 BPOT Royal Mail (1960s) . Railway Vehicle Preservations Ltd. Private owner. 1967
No. 80345 Mark 1 POS Royal Mail (1960s) . Private owner. 1968
No. W80349 Mark 1 POS Royal Mail (1960s) . Railway Vehicle Preservations Ltd. 1968

Question: Which owner has a description of Mark 1 pos and dated 1956 in the List of Central Railway Large Locomotives and British 1 Car Rolling Stock?