Jacob Harris, address in Sunderland

[Dundee]

...... another form dated 15 March1905 references a Dr Anderson of 1 Ward Terrace, which is only yards from Burlington Road. 

Not that it helps, but here is John ANDERSON in 1901.

https://www.familysearch.org/ark:/61903/1:1:XSCH-Y2H

Debra 

[Cas (stallc)]

Welcome to Rootschat 

The 1939 entry that Dundee referred to has Isaac with same birthdate you mention. There is this likely marriage to first wife which would give you a possible father's name for Isaac on marriage cert, (who he states as his father)

Isaac Harris
Registration Quarter   Oct-Nov-Dec 1916
Registration district   Wirral
Inferred County   Cheshire
Spouse   Janie I Mcbirnie
Volume Number   8a Page number   786

There must have been a divorce if he remarried as it looks likely first wife did not die until 1974. Reverted to maiden name.

Name   Janie Isabel McBernie
Death Age   87
Birth Date   29 Apr 1887
Registration Date   Apr 1974
Registration Quarter   Apr-May-Jun
Registration district   Birkenhead
Inferred County   Cheshire
Volume   37 Page   0701

Probate around same address as Isaac in 1939

https://www.rootschat.com/links/01t1y/

Janie Isabel Mcbirnie
Death Date   5 Apr 1974
Death Place   West Caldy Wirral Merseyside
Probate Date   29 Jul 1974
Probate Registry   London

Cas

[Dundee]

Trying to find them in 1921, I went down the rabbit hole with Janie    She was pretty much the last man standing in her family so ended up with a sizeable estate.  She is referred to with the surname HARRIS in her family's wills but used McBIRNIE herself.  They all lived at Westcliffe House.

https://www.youtube.com/watch?v=CI_ctM_3lH4

Debra 

[Cas (stallc)]

Have also looked at index for 1921, don't have full access.

There is a phone directory in 1922 that places her surgery in Market Street under Hoylake. So would expect at least her to be in or around area 1921.

https://www.ancestry.co.uk/discoveryui-content/view/100440609:1025

Cas

[AlanBoyd]

There is a long and detailed article on page 1 of the Liverpool Daily Post, August 8th 1955 about three people drowning at Barmouth as a result of unusual tide conditions. Attached to this article there is an account of a related incident at Meols on the Wirral. Four people rescued from the sea were taken to a nearby holiday camp.

The men were treated by Dr Janie McBirnie who was at the camp.

[Dundee]

They are on electoral rolls in Liverpool at various numbers in Rodney Street with a residential address of 25 Falkner Square, 1921/22.  After that the residential address is The Summit, Caldy (the same as 1939) or Caldy Estate.

Debra 

[Dundee]

Harold PEMBERTON lived next door at 24 Falkner Square if anyone with access wants to have a look 

Debra 

[dah48]

It's over thirty years since we looked at all this stuff - and therefore pre internet access to these databases - so my mind is boggled by all this information that you're digging up. It is all very useful in trying to work out who Isaac Harris was. Isaac and his second wife, Norah, both died in 1959 when my wife was 3.  One of Isaac's older children later went to visit Dr McBirnie at The Summit, Caldy Hill and she couldn't tell them much about Isaac's early life. I need to follow Cas and Dundee's basic advice and get hold of the marriage certificates. 
I am intrigued by bbart's reference to Moses Harris Levy being in the RAF as there is a Barnett Harris mentioned on Jacob's Naturlization certificate of June 1895 and a Barnett Harris who was also in the RAF.

[Cas (stallc)]

The GRO is best to use as reasonable, others can be more expensive. It is £11.00 for a marriage cert at moment.  Marriages are not available (as yet) as digital copies where downloads are instant. Only births and deaths within certain timescale.  Just register and the index is free to search.

https://www.gro.gov.uk/gro/content/certificates/Login.asp

Hope this helps

Cas