Cannot find them in Kellys. however a google search gives https://picclick.co.uk/THORNYCROFT-HP-SAUCE-VAN-HP-REG-RP-112385764941.html which ;lists a postcard which is described thus:
THORNYCROFT HP SAUCE VAN + 'HP' REG. RP POSTCARD BARNETT & COOPER, ASTON. 1920s
£32.00 1 Bid SOLD, £1.75 Shipping, eBay Money Back Guarantee: Get the item you ordered, or your money back!
Seller: nostalgically-yours (40) 100%, Location: Salisbury, Ships to: GB, Item: 112385764941
A very nice, rare or maybe unique, original real photo postcard depicting a Thornycroft van in the livery of the HP Sauce company. We believe the model is the Thornycroft 'X' type. The vehicle displays a very appropriate registration plate; 'HP 797'.
Published by Barnett & Cooper, of 18 Parliament Street, Aston, the postcard is in very good condition for age of almost 100 years - with a crease evident on the right side of the card and it has rounded corners. The photograph is well defined with a good tonal range. A super addition to any HP Sauce related archive or road transport postcard collection.
So presumably they were there in the 1920s, but are not listed in Kellys for 1921, 1924 or 1932
THORNYCROFT HP SAUCE VAN + 'HP' REG. RP POSTCARD BARNETT & COOPER, ASTON. 1920s
£32.00 1 Bid SOLD, £1.75 Shipping, eBay Money Back Guarantee: Get the item you ordered, or your money back!
Seller: nostalgically-yours (40) 100%, Location: Salisbury, Ships to: GB, Item: 112385764941
A very nice, rare or maybe unique, original real photo postcard depicting a Thornycroft van in the livery of the HP Sauce company. We believe the model is the Thornycroft 'X' type. The vehicle displays a very appropriate registration plate; 'HP 797'.
Published by Barnett & Cooper, of 18 Parliament Street, Aston, the postcard is in very good condition for age of almost 100 years - with a crease evident on the right side of the card and it has rounded corners. The photograph is well defined with a good tonal range. A super addition to any HP Sauce related archive or road transport postcard collection.
So presumably they were there in the 1920s, but are not listed in Kellys for 1921, 1924 or 1932