For me, one of the joys of acquiring vintage machines is the ephemera that you find tucked in with it. Because the 401 came in a cabinet, there were 3 drawers full!
These are my favourites its so far:-
* a wonderful (but sadly mostly used up) stocking repair set. I have several different types of these (oh gosh, a sub-collection!)
* some old repairing/cleaning things and a lovely old crunchy Singer paper bag
* a Singer leaflet about cabinets - which has prices written on it in pencil! So in 1963 the '75' cabinet was £25 - 13 - 6. The '363' cabinet (which is what they chose) was £27 - 10 - 6. The other price I think was for the '40Q.A.L.' cabinet (although that's not entirely clear, it could have been the boxy type) was £29 - 9 - 3.
* The original receipt for the machine. 23 March 1963. They traded in an old Singer - got £3 - 1 - 6 in part exchange. The total price, which I presume included the cabinet, was £133 - 1 - 6. That was a lot of money in 1963! They paid £25 up front - perhaps the rest was on weekly terms but there's no more documents about it.
* A hand written recipe for cough mixture was in the same envelope as the receipt
The machine belonged to one lady all her life until she moved to a carried home. It was then sold by her daughter to a work colleague. And then to me. It has stayed in the Greater London area the whole time until I brought it home to the West Country.