A T-Type will not give up its fastenings to a modern socket set, and the reason is a piece of history rather than an inconvenience. Inside the engine and gearbox the threads are metric. The heads are not. Knowing that before you start saves buying the wrong tools twice.
Metric threads, Whitworth heads
Every nut, bolt and stud inside the engine and gearbox has a metric thread. The heads were made to Whitworth sizes, because the British mechanics who would be working on these cars had Whitworth spanners and no metric ones. The commonest threads are 8 x 1 mm and 10 x 1.5 mm, with 5 x 0.7 mm, 6 x 1 mm and 12 x 1.5 mm also present.
The practical consequence is that a thread which looks imperial is not. If you are replacing a stud, chasing a thread or buying a fastener, measure it rather than reading it off the spanner that fits the head.
Outside the engine, and what changed
On an early TD, most of the remaining nuts and bolts are either BSF, the fine thread, or Whitworth, the coarse one. A set of Whitworth spanners fits both, and fits the metric fasteners inside the engine and gearbox as well, which is why one set covers most of the car.
On later TDs and on all TFs the same fasteners are used, but some of the BSF threads are UNF instead. Those need AF spanners, measured across the flats, most commonly 7/16, 1/2 and 9/16 AF. In the United States these are compatible with ANF.
The wheel nuts changed from BSF to UNF at some point during TD production. Jones does not give the change point and the archive has not been able to establish one, so check the car in front of you rather than its build date.
What you actually need
Whitworth spanners and sockets, AF spanners if the car is a later TD or a TF, a set of feeler gauges and a grease gun. Beyond those, and the two tools below, a T-Type needs very few special tools, which is one of the reasons it remains a good car to maintain at home.
The two you cannot do the brakes without
A large socket for the rear brake drum hub nut. On the TF this is 1.25 in AF, or 32 mm. Jones records that the early TD used a large BSF nut and that he has no record of its size; neither has the archive been able to find one, so if you know it, please get in touch.
What makes this one matter is not access but torque. A hub nut that is not tightened correctly lets axle oil past and onto the rear brake shoes, and the first you know of it is the car pulling under braking and the drum having to come off again.
A hub puller, for both front and rear drums. The trap here is that most garages hold pullers for four-hole wheels, and TD and TF wheels have five, so one borrowed rather than bought may simply not fit. Jones made his own for his TF.
His photographs also show a hole in the brake drum aligning with one in the wheel, giving access to the rear brake shoe adjuster without taking either off. Whether that is original or his own work the book does not say, and the archive is not going to guess.
Sources
Barrie Jones, MG TD, TF & TF1500: 1949–1955, The Essential Buyer's Guide, Veloce Publishing, ISBN 978-1-845843-52-6, page 58, for the thread practice, the spanner sizes, the hub nut size and the puller.
The thread and fastener detail here is reported from a single named source. If your car disagrees with it, the archive would rather hear about it than be quoted.
Read next
See drum brakes, adjustment and bleeding, chassis greasing, chassis and engine numbers, parts and spares, and the technical library.