In message , Bill
writes
This is cut and pasted from an invoice. If I remember the micrometer, I
will take more measurements

2 of R3001E Primed Eared 75mm Cast Iron Downpipe x 1.83m length @
£99.70
10 of R0004 100mm Pipe Nails @ £4.10

OK, this pipe is 69.4 mm internal dia, 79.96 O/D. The larger socket end
into which the next section of pipe fits is 84.50 mm internal.

I also measured the old pipe from the wall, which we believe is the
original from approx 1890.

It is internal 66.5, external 77.85 and the larger socket end (and the
original cast hopper receiver 84.2 internal, all to include rust etc.
--
Bill