Highbury Park

Below are the two sides of a small piece of paper. One side reveals it is probably a sixth or an eight of a document from the romanian consulate in Antwerp. There are several of such documents (in diffferent states of conservation) in the binder :

On the other side is an adress in London : 

which I read as

S Saperstein
125 Higbhry Park 5
London

very difficult to decypher beneath the line ; "11 Kay" ?

We know from this card that Eisik most probably went to London between 1922 and 1935. What does Internet research on the above name and address reveal ?
I assume that Higbhry is a notation of Highbury.

This brings us to "125 Highbury Park" (Also guessing that the "5 London" on the card stands for N5 today ):

Unfortunatelly I have not been able to look furhter what this adress reveals around the 1930's.

Letter from the Home Office, UK

This paper of which about only the upper third remains raises more questions than providing any answers.

click to enlarge

It emanes from the Home Office in London, is adressed to Eizik Kahan and holds a reference number K.10856. It is dated April 28th, 1938.

Today the Home Office defines its missions as (link)

The Home Office leads on immigration and passports, drugs policy, crime policy and counter-terrorism and works to ensure visible, responsive and accountable policing in the UK.

The seal in the middle represents a Union Jack flag around which is written "National Scheme for Disabled Men". Some research on the net learned that this seal was granted to those employers (in this case the Hoome Office) that employed a minimum percentage of disabled men from the first World War.

I have found in Eisik's passport a stamp for a visa to the UK in september 1938. I will come back to this later in another post where I will scrutinize all stamps and dates of the passport.

The object of this letter remains hidden to me. I understand the passport is directed to be returned with an endorsement. That endorsement has a condition attached, but the text is missing.

What was the original request ?
In which (immigration) procedure was this part of ?
What were the UK regulations regarding east european jews in 1938 ?

many questions...