What exactly are you trying to push pull? If its the formation from Tees Valley - the 101 is dead coaching stock in the formation and the power comes from the 31 - if you want to go the other way - you still need to control from the 31 (either by reversing or coupling to the other end and changing cab).
7 cars of mk2a intercity , around 400t I mean , even in double unit , the tail class 31 isn't oparating .ONLY the first unit runs (when control cutout switch = cut out in tail)
As far im aware those mk2s are not equipped with a control jumper cable through the entire train. You have the cable for the el. Heating.
In the UK, ordinary coaching stock has - at most - the "UIC cable" which is primarily to carry and control the ETH supply from the locomotive to the train. The control function has been used in some countries (notably Germany) to also control carriage features such as power doors from the locomotive. It is also possible to fit locomotives to carry driving controls information over this cable. In the UK, this is primarily done to allow a DVT's cab to control a locomotive at the far end of the train, rather than for two locomotives to work in tandem. Only a few types of locomotives are fitted with this "TDM equipment" in addition to what would be required just for ETH supply, and the 31s are not among them. Of the BR-era locos, classes 87, 90, 91, and subclass 47/7 can be expected to have TDM fitted; the few HST power cars with nose-end buffers also have (or at least once had) TDM equipment from their days serving as surrogate DVTs in the first IC225 sets. There was a minor exception to this rule - on the Edinburgh-Glasgow route in the 1970s, pairs of Class 27s were used top-and-tail, with their normal "Blue Star" multiple-working controls wired through the carriages rather than the later TDM system. Locomotives fitted for this operation were designated subclass 27/1 and 27/2. Indeed the carriages were originally still steam-heated and didn't have an ETH cable; the replacement of the steam-heat boiler with an ETH genset required the further redesignation of locomotives to subclass 27/2, trains then being formed with a 27/1 at one end and a 27/2 at the other (so the multiple-working system must have remained the same). This whole operation was a very specific conversion and was not normal practice in the UK, except for dedicated trainsets such as the HST (which was originally classified as a DEMU). These 27s were worked very hard and became unreliable, and were subsequently replaced by 47/7s.
