Bristol Postage Dues - part 4

Finally (for the moment) here are some slightly later postage dues from Bristol.  I'm not clear why the top postcard sent in 1920 franked with the international postcard rate at the time of 1d, was marked with the Bristol hexagonal tax mark, but by 1931, the date of the lower postcard, the international rate had risen to 1½d so the postcard was underfranked.

Below are more examples from when the domestic postcard rate had risen.  The lower postcard has the later style charge mark, "1D / TO PAY / 134" rather than the olderstyle "2D / 134" of the top card.

... again the examples below are international postcards only franked at 1d when the rate had risen to 1½d.

The envelope below sent in December 1948 has a Canadian meter mark that was flagged with a turquoise "T / 6 / CENTIMES" tax mark which was translated in to 1½d to pay - indicated by 1d and ½d "TO PAY" charge marks.  The postage due stamps were cancelled by straight line cancels, a type of cancel also known used in 1940.

The two underfranked international postcards below have the later style "TO PAY" charge marks.  The lower card from 1954 also has a black framed "INSUFFICIENTLY / PREPAID" cachet.

Here is another example of the "TO PAY" charge mark and framed "INSUFFICIENTLY / PREPAID" cachet, this time on a domestic postcard from 1951.  The domestic postcard rate increased to 2d in May 1940.