This is the bicycle type clip for the original MK1/2 shape windscreen washer bottle. From about 1964 onwards.
The bracket for bottle is 37H9712ORIGINAL.
The original Winguard MK1/2 bottle part number was ADA3833, now 17H2536.
MK1 uses 2 wire clips, see 37H9672.
MK2 uses 1 bicycle wire type clip, see 24A1387.