Unfortunately there is no single list in the UK for internees. The National Archives have a guide which covers the various items they hold, both of internees and those exempted for internment, but there is very little available in UK sources for WWI and what is available is often neither online nor easily searchable.
They do also direct us to the International Committee of the Red Cross, who now have an online search for index cards of prisoners of war / internees (military and civilian) right across the war.
You must indicate their nationality and what type of record, then surname, then look for the correct entry card in a mostly-alphabetical list. When searching 'Spranger' for example, it lands us on the 'Spreng-' section and you have to go a bit backwards.
This leads us to Paul's record. The original card is dated 11.9/15, but it's not clear to me if this is the date of internment or the date of first record.
You can then search for the various numbers marked on his card which indicate other records - the search box is to the right. The two I could find:
D127-13 (search for D + 127 then scroll down) - list of those interned. He is listed as at "Stfd." which according to this glossary indicates Stratford, with a date in 1917, and a note in French I think marking pretty much everyone on the page as having been repatriated.
All LII 7 = search for 'All 52', page 7. Gives an address for him in Crouch End, as well as Cottbus, Brandenburg (B) - possibly his birthplace?
Stratford camp held many men who had settled in East London, started businesses and raised families. It apparently did not have a good reputation.