Are there any rules and regulations that need to be adhered to at the stadium? I would like to bring a 5ft x 3ft flag and a 3ft x 2ft one (both are meant to be hung over railing).

I imagine 5ft x 3ft would be fine?

Better to be safe than sorry.

Depends where you're wanting to put it.

There is no way of switching between the tiers so if you're in the bottom tier then you can't put it anywhere as they won't allow them to be tied to the barriers at the front. (what we were told by Wembley last year, but we did want to take 25)

If you're in the top tier then you should be fine to tie it up as long as it isn't covering sponsors.

heres some info

GUIDANCE FOR USE OF FLAGS AT WEMBLEY STADIUM
Wembley Stadium recognises that many supporters like to display flags when attending
events. The following guidance has been created to assist visitors in ensuring their flags
meet with the health & safety standards & ground regulations of the Stadium.

SUPPORTER FLAGS
• Flags more than 250cm in size at their widest or longest section or flagpoles greater
than 1m in length are not permitted.
• Flags should be positioned so as not to obstruct gangways, access routes, exits and
entrances, health and safety signage or stairways.
• Wembley Stadium reserves the right to confiscate flags if they are very large or may
compromise public safety, obscure someone’s view, a camera position or if a flag
carries offensive, discriminatory or inflammatory messaging.
• Any articles that could potentially be used as a weapon and/or compromise public
safety are strictly prohibited.

CROWD FLAGS
• Permission must be sought in advance from the Stadium and event owner to arrange
use of the very large supporter flags that are designed to be passed over people's
heads.
• In such cases the flag must be flame retardant and the organiser bringing the flag into
the stadium will need to provide the appropriate H&S certification and method
statements detailing how the activity will be undertaken.
• Crowd flags cannot be carried through public turnstiles.
• Crowd flags can be used in level 1 of the Stadium only and the release and capture of
the flag must be done in a controlled fashion. The event owners designated
entertainment company may be able to assist in managing this activity on your behalf.
• It is the Stadium’s experience that larger flags travel across the crowd better and are
easier to manage than smaller flags. This is because the direction of travel cannot be
controlled by individual fans. It is therefore recommended that flags are no smaller than
12m x 12m in size, with flags as large as 15m x 30m operating successfully in the past.

We did all that and they still said no