What would happen if you did a Heathrow inter-terminal transfer by tapping in and out on EL/HX?

[signed]

The Heathrow website reads (from T4 to T5) :

Free London Underground services run from Heathrow Terminal 4 to Heathrow Terminal 5 (change at Heathrow Terminals 2 & 3). You will need an Oyster card or simply use contactless payment. No charge applied if you only travel between terminals.

Free Heathrow Express or Elizabeth Line trains run from Heathrow Terminal 4 to Heathrow Terminal 5 (change at Terminals 2 & 3). Please obtain a free Inter-terminal transfer ticket from the ticket machines in the station.

I assume it's a misnomer and that Contactless/Oyster is valid for free inter-terminal even on NR, but what would happen if you used Contactless/Oyster on NR?

 

[JonathanH]

I assume it's a misnomer and that Contactless/Oyster is valid for free inter-terminal even on NR, but what would happen if you used Contactless/Oyster on NR?

There is no charge. This is confirmed on the single fare finder.

However, the point of the wording you picked out in bold is that you don't need Oyster or Contactless to make this free journey, but you do have to go through ticket gates.

 

[signed]

There is no charge. This is confirmed on the single fare finder.

That was what I figured, thanks