Many thanks for you input.
Just to add a bit more information. This new rack I’ve purchased is listed as part No. 305932 (All Other models – Standard) on Rimmers web site. The other rack they list is No. 305458R and is for model Herald 948.
The measurements of this new rack, overall length and the distance between the flanges, are the same as a NOS part No. 305932. So although it is a pattern part I believe it’s been made correctly and it would be fine if you needed that number.
The part number which could be relevant to my vehicle is 305050, which is longer available. This is from the spare parts catalogue Herald 1200 Saloon & Coupe (1st Edition).
Hugh